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ACKNOWLEDGMENTS 

The author gratefully acknowledges the assistance of individuals 
listed below on one or more aspects of ants discussed in this bulletin : 
Allen Mclntosh (now retired), and J. A. Fluno, U.S. Department of 
Agriculture, Beltsville, Md. ; H. T. Vanderf ord, Georgia State Board 
of Entomology, Atlanta; J. C. Moser, Southern Forest Experiment 
Station, U.S. Department of Agriculture, Alexandria, La.; Arnold 
Van Pelt, formerly with Tusculum College, Greeneville, Tenn. ; 
Mary Talbot, Lindenwood College, St. Charles, Mo.; M. S. Blum, 
Louisiana State University, Baton Rouge; and M. H. Bartel, 
Kansas State University, Manhattan. He is indebted for the illustra- 
tions to Arthur D. Cushman and the now deceased Sarah H. DeBord. 
Some of the illustrations have been used previously (Smith, 1947, 
1950). 

Cover illustration : Worker of black carpenter ant Camponotus penmylvantouii 
(DeGeer). 



HOUSE-INFESTING ANTS 

of 
THE EASTERN UNITED STATES 

Their Recognition, Biology, and Economic Importance 

WJLOAM L. BROWN 



By 

Marion R. Smith 
Entomology Research Division 



Technical Bulletin No. 1326 



Agricultural Research Service 
UNITED STATES DEPARTMENT OF AGRICULTURE 



Washington, D.C. Issued May 1965 

For sale by the Superintendent of Documents, U.S. Government Printing Office 
Washington, D.C., 20402 - Price 48 cents 



Contents 



page 

Introduction 1 

Classification and Bionomics 2 

Economic Importance 4 

Collecting, Shipping, and Identifying Ants 7 

Key to Subfamilies of Formicidae , 9 

Keys to Species 10 

Discussion of the Species 17 

Labidus coecus (Latreille) 17 

Neivamyrmex nigrescens (Cresson) 18 

Neivamyrmex opacithorax (Emery) 19 

Aphaenogaster lamellidens Mayr . 20 

Aphaenogaster rudis (Emery) 21 

Aphaenogaster tennesseensis (Mayr) _ 23 

Aphaenogaster fulva Roger 24 

Pheidole bicarinata vinelandica Forel 25 

Pheidole floridana Emery 26 

Pheidole dentata Mayr 27 

Crematogaster ashmeadi Mayr 28 

Crematogaster cerasi (Fitch) 30 

Orematogaster clara Mayr 31 

Crematogaster lineolata (Say) 32 

Monomorium minimum (Buckley) 33 

Monomorium pharaonis (Linnaeus) 34 

Monomorium floricola (Jerdon) 36 

Monomorium destructor (Jerdon) 37 

Solenopsis xyloni McCook 38 

Solenopsis geminata (Fabricius) 40 

Solenopsis saevissima richteri Forel 41 

Solenopsis molesta (Say) 43 

Tetramorium caespitum (Linnaeus) 45 

Tetramorium guineense (Fabricius) 47 

Wasmannia auropunctata (Roger) 48 

Atta texana (Buckley) 50 

Iridomyrmex humilis (Mayr) 52 

Iridomyrmex pruinosus (Roger) 54 

Dorymyrmex pyramicus (Roger) 56 

Tapinoma sessile (Say) 57 

Tapinoma melanocephalum (Fabricius) 59 

Camponotus castaneus (Latreille) 60 

Camponotus tortuganus Emery 62 

Camponotus pennsylvanicus (DeGeer) 63 

Camponotus ferrugineus (Fabricius) 67 

Camponotus abdominalis floridanus (Buckley) 69 

Camponotus caryae discolor (Buckley) 70 

Camponotus nearcticus Emery 72 

Camponotus rasilis Wheeler 73 

Paratrechina longicornis (Latreille) 74 

Paratrechina (Nylanderia) spp 76 

Prenolepis imparis (Say) 78 

Lasius alienus (Foerster) y 

Lasius neoniger Emery 81 

Lasius umbratus (Nylander) 84 

Acanthomyops claviger (Roger) 86 

Acanthomyops interjectus (Mayr) 88 

Acanthomyops murphyi (Forel) 89 

Acanthomyops latipes (Walsh) 91 

Glossary 93 

Bibliography 98 

ii 



HOUSE-INFESTING ANTS OF THE EASTERN 
UNITED STATES: 

Their Recognition, Biology, and Economic Importance 

By Marlon R. Smith, 1 entomologist, Entomology Research Division, Agricultural 

Research Service 

INTRODUCTION 

Each year numerous requests for information on the identification 
and control of house-infesting ants are received by various Federal 
and State agencies, colleges and universities, boards of health, and 
pest-control operators. Individuals in these organizations who handle 
such requests find themselves greatly handicapped because of the lack 
of comprehensive literature dealing with common house-infesting ants. 
Often they are unable to identify the ants either to genus or species. 
This bulletin has been prepared to take care of some of the needs of 
technical and semitechnical workers. However, no attempt has been 
made to cover the highly specialized field of ant control. Originally, 
I had hoped to include all house-infesting ants of the United States. 
Because of the lack of knowledge of these ants in several regions, espe- 
cially western North America, it was thought best to include only ants 
of the eastern United States. However, many of the ants discussed 
occur also in the Western States. 

In this bulletin I have furnished keys to species, based on workers 
of all the well-known, house-infesting ants of the eastern United 
States. Each species is fully described and figured, and its biology 
and economic importance discussed. I have also given the available 
common names of the species (including those approved by the Ento- 
mological Society of America) ; stated whether the ant was intro- 
duced, and if so, its probable original home ; outlined its range of dis- 
tribution, especially in the United States; and indicated whether it 
has been confused with other species. Technical terms are given in 
a glossary. Important references are listed under each species and 
also in the bibliography. Because the biology of only a very few ants 
has been intensively studied, much of the information given is based 
on miscellaneous observations. Although the bulletin deals primarily 
with ants as house pests, every way in which a species is known to be 
inimical to man is also mentioned. 

When ants infest a house, they may be represented by workers, 
females, or males, or any possible combination of these castes. Since 
the worker is the most common, troublesome, and best known, this 
bulletin deals with it only. 

Smith (1943) presents a means of identifying males to genus, and 
Creighton (1950), of females and workers to species. However, the 
identification of males and females to species is a difficult task and is 
not generally recommended. 

i Retired. 



2 TECHNICAL BULLETIN 1326, TJ.S. DEFT. OF AGRICULTURE 

Classification and Bionomics 

Ants belong to the order Hymenoptera, which also includes the 
wasps and bees. The ants comprise the family Formicidae, and are 
distinguished from their nearest relatives by two important charac- 
ters : One of these is the differentiation of the abdomen into two well- 
marked regions a slender, one- or two-segmented, freely moving ped- 
icel, and a larger, more compact terminal portion, the gaster ; the other 
separating character is the elbowed antenna, in which the first seg- 
ment, or scape, is greatly elongated in both the female and the worker. 
In the male, the antenna frequently does not appear to be elbowed, 
since the scape is not always noticeably lengthened. 

Ants can be distinguished from termites, with which they are com- 
monly confused, by the strong constriction or "waist" between the 
thorax and the abdomen, and the two pairs of wings of which the an- 
terior pair is much larger than the posterior pair, 'both having few 
veins. Termites, on the other hand, have two pairs of wings, approxi- 
mately equal in size with numerous veins. They have a tendency to 
lose their wings more readily than the ants. Termites also differ from 
the winged ants in that the abdomen is broadly joined to the thorax. 

There are normally three distinct castes of ants : Workers, females, 
and males. The male is generally winged, and retains its wings until 
death. Its size is usually intermediate between that of the worker and 
the female, and the male is characterized by its protruding genital 
appendages, the presence of ocelli, poorly developed or vestigial man- 
dibles, and extraordinarily large eyes, which are out of proportion to 
the remainder of the head. Apparently, the sole function of the male 
is to mate with the unfertilized female ; when mating has been accom- 
plished, the male perishes. Mating may take place in the nest, on the 
ground, or in the air. Males are produced in old or very large colonies 
only, where there is an abundance of food, since much nourishment 
is required to bring males to maturity. After attaining maturity, the 
male usually does not remain long in the parental nest. After leav- 
ing it, he may even succumb to predators and the elements without 
having mated. 

The female, generally the largest of the three castes, normally pos- 
sesses wings but loses them after mating. She usually possesses three 
ocelli in addition to the pair of large compound eyes, a large thorax 
to accommodate the two pairs of wings, and a large abdomen for the 
production of numerous eggs. The primary function of the female or 
queen is reproduction, but in many of the more highly specialized ants, 
the queen also cares for and feeds the first brood of workers on her 
salivary secretions. She may live for many years ; upon her death she 
is commonly replaced by a daughter queen. However, ants may have 
one or more queens, according to the species. 

The worker, which is also a female, is never winged except as a rare 
abnormality. The workers of most species lack ocelli. The thorax 
is simple, apparently composed of three segments, but in reality there 
are four. Workers are not always of the same size or morphological 
structure in a given species. When workers are of approximately 
the same size and structure within a species, we say the species is 



WILLIAM L. BROWN 

HOUSE-INFESTING ANTS OF THE EASTERN UNITED STATES 3 

monomorphic (one form) (example: the Argentine ant Iridomyrmex 
humilis (Mayr) ) . When workers within a single species display two 
distinct sizes and structures, we say the species is dimorphic (two 
forms) (example: Pheidole dentata (Mayr)). When the workers 
within a species are of varying size and structure, from small through 
intermediate to large, the species is termed polymorphic (many 
forms) (example : fche black carpenter ant Camponotus pennsyl/uanious 
(DeGeer) ) . The function of the worker is to construct and repair 
the nest, feed the immature and adult ants of the colony including 
the queen, care for the brood, and defend the nest. Formerly it was 
thought that workers seldom, if ever, laid eggs. If they did so, the 
eggs, being unfertilized, would, as in the honey bee, develop into males. 
Recent evidence appears to indicate that workers of most, if not all, 
ant species lay eggs, and that the eggs of at least some species can 
produce workers and females, as well as males. However, our knowl- 
edge of this subject is very limited and much more study is needed. 

Ants have four developmental stages : Egg, larva, pupa, and adult. 
The egg is almost microscopic in size, varying in shape according to 
the species. It may be spherical, broadly elliptical, or cylindrical. 
On hatching, it produces a soft, legless larva. The larva may also 
vary in size, shape, and pilosity according to the species. One of 
the most common forms is more or less translucent, gourd or squash- 
shaped, with the head borne at the narrow end. In shape, the pupa 
resembles the adult that it is to become, but differs from the adult in 
being soft, unpigmented, and lacking in power to move from place to 
place in response to warmth, light, and humidity. In some species of 
ants, all of the pupae are naked ; in others, the pupae are borne in 
cocoons spun by the larvae; and in still others, the pupae are both 
naked and enclosed. The cocoons are papery or parchmentlike. 
When an individual within a cocoon transforms to the adult, it may 
emerge without help, or it may require assistance by the workers. 
Queen pupae are the largest of all, and can be immediately recognized 
by their unusually large thorax and abdomen, the former bearing 
wing pads. Male pupae, which are somewhat smaller than queen 
pupae, can be distinguished by their wing pads and protruding genital 
appendages. Worker pupae are the smallest of all, and resemble adult 
workers except for their pale color, soft body wall, and incapacity to 
move about. 

The adult, after emergence, may require a few days to attain com- 
plete maturity. While lacking full body color and hardness of the 
body wall, the ant is commonly known as a "callow." Frequently, 6 
weeks to 2 months or more are required for development from the egg 
to the adult stage, the time depending largely on the season of the year 
and the temperature. 

There are a number of ways by which ants may establish new colo- 
nies. One is a process known as splitting or budding, in which a ferti- 
lized daughter or queen leaves the parental nest accompanied by a 
number of sister workers who aid her in establishing and carrying on 
the functions of a new colony. Such a process is common to the le- 
gionary ants, Neivamyrmex nigrescens (Cresson) and N. opacithorax 
(Emery) . Another way is a form of temporary parasitism, in which 
a fertilized female or queen of one species seeks, and may obtain, adop- 



4 TECHNICAL BULLETIN 1326, U.S. DEPT. OF AGRICULTURE 

tion in a colony of another species of ant, called the "host ant." This 
may be accomplished in several ways: (1) By entering a queenless 
colony of the host species, (2) by killing the queen of the host species 
herself, or (3) by inducing the workers of the host species to kill their 
own queen. In every case the end result, if successful, is the same ; the 
queenless colony of the host ant accepts the alien or invading queen. 
Such temporary parasites include Lasius umbratus (Nylander) and 
probably some of the species of Acanthomyops. Their hosts are usu- 
ally common species of Losing (Lasius} such asalienus (Foerster) and 
neoniger Emery. One of the most common methods of establishing a 
new colony is for the fertilized queen ( after losing her wings, forcibly 
or otherwise) to construct, or enter a preformed cell or cavity in wood 
or under the bark of a stump or log, close the chamber, and rear her first 
brood (unaided by workers) from the nourishment supplied by her 
salivary glands. The small, undernourished workers, which compose 
the first brood, then open up the nest and bring in food from the outside 
for the queen, her brood, themselves, and for future broods. As the 
colony becomes older and the amount of food greatly increases, more 
and larger workers are successively produced, and soldiers, females, and 
males appear. To attain this state of maturity, in which a colony may 
contain several thousand workers, many males and females, and in- 
numerable 'brood, requires a long time perhaps 3 to 5 years or more. 
After attaining this state of maturity, a colony may continue to pro- 
duce these castes and immature stages for a number of successive years ; 
just how long, we do not know. The method herein described is typical 
of many species of ants, especially the species of Camponotus, includ- 
ing our common black carpenter ant O. pewnsylvanicus. 

Economic Importance 

Ants are among the most common and abundant of all our insects. 
The probable reason for their success is that they are highly adaptable 
to different environments, foods, and nesting sites, and possess great 
reproductive ability, hardiness, and alertness. These attributes cause 
ants to be one of man's chief insect competitors, and inimical to him in 
numerous ways. Ants may affect man adversely by infesting his house 
or buildings, where they may cause annoyance by feeding on human 
foods, or cause structural damage by their nesting activities. They 
mar the appearance of lawns, golf courses, and parks with their numer- 
ous and unsightly nests, steal seeds from seed beds, feed on seeds 
whether the seeds are germinating or not, defoliate plants, and gnaw 
into various parts of plants, especially roots and buds. They foster 
and spread other injurious insects such as plant lice and mealybugs, 
which in turn may injure the plant directly by their feeding activities 
or may spread a plant disease from an infected to a healthy plant. 
They may gnaw holes in various types of cloth, fabrics, and certain 
rubber goods, or remove the rubber insulation from telephone and elec- 
tric wires, or damage the wiring of other electrical equipment. Ants 
sometimes kill young poultry or other birds, and small mammals, and 
occasionally may act as intermediate hosts for parasites of birds and 
small mammals. They are especially annoying because of their biting 



HOUSE-INFESTING ANTS OF THE EASTERN UNITED STATES 5 

or stinging. The effects on a human are dependent upon the number 
of attacking ants, and that person's degree of allergy. Ants may also 
spread such human diseases as dysentery, typhoid fever, or tubercu- 
losis by feeding on and crawling over sputum, faeces, and carrion. 

The importance of ants as pests cannot be overestimated. For in- 
stance, during one year the total amount of literature issued to the 
public on ants ranked sixth among U.S. Department of Agriculture 
publications. A former head of an entomology unit within the De- 
partment of Agriculture informed me that requests for information 
on ant identification and control ranked very high among the total re- 
ceived for a number of years. At a very early date, the U.S. Depart- 
ment of Agriculture recognized the importance of ants as pests, and 
issued publications on them (certainly as early as Marlatt, 1898). In 
the early publication referred to, three species were discussed: The 
Pharaoh ant Monomorium pharaanis (Linnaeus) , the small black ant 
Monomorium minimum, (Buckley), and the pavement ant Tetramo- 
rium caespitum (Linnaeus). They were briefly discussed as to recog- 
nition, biology, economic importance, and control. Since that date, 
the Department has periodically issued bulletins and circulars by 
various authors on house-infesting ants, as well as on those affecting 
ranges, orchards, forests, field crops, and agriculture in general. 
Many, if not most, of our States have issued similar publications, espe- 
cially on house-infesting ants. 

I am convinced from my nearly 50 years of experience with ants that 
few homes escape infestation over a long period of years, and that in- 
numerable homes suffer almost constant or recurring infestations. 
The degree to which such homes suffer may vary from almost negli- 
gible to severe. An ant like the Pharaoh ant Monomorium pharaonis 
(Linnaeus), or the Argentine ant Iridomyrmeai humUis (Mayr), may 
be an almost continuous pest over months or even years, whereas other 
species may infest a house on rare occasions and only for a limited 
time. Frequently, infestations of the latter kind will cease abruptly 
of their own accord without obliging the housekeeper to resort to 
control measures. House-infesting ants may be likened to common 
colds everyone is subject to them, and while they may be very an- 
noying, the damages suffered are usually of short duration and are 
seldom severe. 

During the 25 years that have elapsed since I bought a new, mostly 
brick home, the structure, especially the kitchen, has been infested by 
seven species of ants: Crematogaster cerasi (Fitch), Solenopsis mo- 
lesta (Say), Monomorium minimum (Buckley), Tapinoma sessile 
(Say), Lasius alienus (Foerster), Tetramorium caespitum (Linna- 
eus), and Camponotus castaneus (Latreille). The last-named species 
appeared only once in the house, fed on angel cake, and left of its own 
accord. All the other ants have infested the house at various intervals 
during warm weather over a long period of years. Occasionally two 
species have infested the kitchen at once, but the species were not in 
close contact with each other. M. minimum was found nesting in the 
soil near the foundation wall below the kitchen, and . molesta in a 
rotten plank of a small porch adjoining the kitchen. T. sessile showed 
a fondness for sweets, whereas 'S. molesta and M. minimum fed on, 
meats, grease, or crackers with much shortening. The most persistent 



6 TECHNICAL BULLETIN 1326, U.S. DEPT. OF AGRICULTURE 

and annoying of all the ants was C. cerasi, which originally nested in 
a locust tree (riddled with burrows of Megacyllene robiniae (Foers- 
ter) ) growing within a few feet of the front of the house. After the 
tree was removed, the ants occurred in great numbers on the English 
ivy that covered most of the walls of the house. The ants seemed to 
derive most, if not all, of their food from the honeydew excreted by 
aphids on these vines. At this time I could not be sure where the ants 
were nesting, but I did see them enter and leave small holes in the 
mortar between the bricks composing the walls of the house. I am 
strongly of the opinion that many of the holes were made by the ants 
themselves. After having had ivy on the house for many years and 
frequent trouble with ants invading the kitchen, I decided to remove 
all the ivy except a small amount on the front of the house. After 
that, the ants ceased to infest the kitchen, and I cannot now recall 
when I last had an infestation there. 

Housekeepers frequently wonder why they have ants in their homes, 
and are greatly perplexed as to where they come from. Ants are often 
accidentally brought into the house by the housekeeper herself; for 
example, on firewood stored in the basement. Such firewood, if faulty 
or in the proper stage of decay, can harbor colonies of the carpenter 
ant Camponotus spp., acrobatic ants (Crematogaster spp.) , and others. 
Stray workers of many species of ants can be brought into the house 
on fruits from the orchard, vegetables from the garden, or even on 
laundry baskets from the yard. Small species like the Pharaoh ant are 
ideally adapted for new nesting sites, and can be transported in parcel 
post packages, grocery packages, trunks, and other objects. Most ants 
nest in the soil, in wood, or in other places outdoors, and infest houses 
from there. Sometimes it is possible to locate the outside trail leading 
from the ant's nest to the house, but in many cases this is very difficult or 
impossible. Infestations originating outdoors normally occur in the 
warm seasons of the year and are, as a rule, seldom severe or long- 
lasting. Several species of ants that normally nest outdoors, have 
become adapted to nesting in the woodwork or masonry of houses. 
Their presence in such places can often be determined by the frequent 
and numerous individuals seen at various periods of the year, even 
during cold weather, and by extraneous material such as wood fiber, 
gravel, seeds, and bodies of dead insects thrown out from holes in the 
woodwork and masonry. At certain periods of the year, the colonies 
may give rise to numerous winged males or females, or both; house- 
keepers often mistake them for termites (see p. 2) . 

Although sanitation and care will frequently keep ants from infest- 
ing a home, they are not sure preventives. Any housekeeper who fails 
to wash her dishes and pots immediately after they are used, or who 
leaves open containers on the cabinet, shelves or tables, or allows chil- 
dren to spill food on the table or floor, is simply inviting ant trouble, 
Care should be taken at all times to keep from accidentally bringing 
ants into the house from outdoors, or from having them infest the 
house because of dirty dishes, open containers, or food carelessly spilled. 
If a homeowner allows certain areas of the woodwork of the house to 
become faulty or rotten from moisture or other causes, various species 
of ants may be expected to colonize there, especially the black carpen- 
ter ant Camponotus pennsylvanicus (DeGeer), lesser carpenter ants 



HOUSE -INFE STING ANTS OF THE EASTERN UNITED STATES 7 

Camponotus (Myrmentoma) spp., and certain species of acrobatic 
ants, Orematogaster spp. Piles of litter or compost, if left undisturbed 
for any length of time, form ideal nesting places for such ants as the 
Argentine ant Iridomyrmex humilis (Mayr), the odorous house ant 
Tapinoma sessile (Say), and the southern fire ant Solenopsis xyloni 
McCook. The general environment outside the house, both natural 
and man-made, has a great deal to do with whether or not the house 
will be infested ; and if so, by what species of ants. Houses in heavily 
wooded areas, for instance, are especially subject to infestation by the 
black carpenter ant, whereas homes in open areas may expect infesta- 
tions from such ants as the southern fire ant Lasius neoniger Emery, 
and others. 

Collecting, Shipping, and Identifying Ants 

The ideal way to submit ants for identification is to place a number 
of clean, uncrushed, live specimens in a 70-percent (or higher) solu- 
tion of ethyl alcohol in a small bottle or vial. The ants will die within 
a few minutes. Never use formaldehyde because this chemical is too 
irritating to the eyes and nose of the determiner. Cheap cologne or 
bay rum will serve, but only as a last resort. The bottle or vial should 
then be carefully wrapped in soft paper, cotton, or similar material 
and enclosed in a fully addressed mailing tube or strong cardboard 
box completely addressed to the individual or organization expected 
to make the identification. The name and address of the sender should 
always appear, and the addresses should be legible. The ants them- 
selves should never be placed directly in contact with loose cotton 
because their antennae, legs, maxillary and labial palpi become en- 
tangled in, and broken py, the cotton fibers ; without these appendages 
in perfect condition it is very difficult, often impossible, to make ac- 
curate determinations. If preserving fluids are not available, place the 
specimens between layers of soft paper, such as facial tissue, and en- 
close in a small but strong cardboard box or mailing tube. An ac- 
companying letter should give all possible details concerning the in- 
festation, especially whether or not the ants have previously infested 
the house, and if so, for approximately how long ; what areas are in- 
fested, the period or periods of the year during which the infestations 
occur, nature of damage, foods preferred, and whether the ants are 
nesting inside or outside the house. 

The specimens described in this paper were studied with a Spencer 2 
stereoscopic binocular microscope equipped with 9 X oculars and 
2.3, 4.8, 6.8 objectives, which gave magnifications of 20.7 X, 43.2 X, 
and 61.2 X, respectively. The magnification most commonly used was 
43.2 X for ants varying in size from approximately 2.5 to 6 mm. ; above 
this size the 20.7 X magnification seemed best for the very large ants, 
such as species of Gamponotus. . The light employed was a General 
Electric 2 No. 82 bulb. These data are furnished because it is very 
important that the person who is identifying ants either have similar 



3 Mention of a proprietary product In this publication does not constitute a guarantee or 
warranty of the product by the U.S. Department of Agriculture and does not Imply Its 
approval by the Department to the exclusion of other, products that may also be suitable. 



8 



TECHNICAL BULLETIN 1326, U.S. DEPT. OF AGRICULTURE 



equipment or know that the ants may not appear exactly as described 
if different magnifications or light intensities are used. 

It is often necessary to examine a subject from several aspects to 
determine such characters as the exact color and shape, or the 
degree of sculpturing. It is recommended that, if possible, more 
than one individual be studied, since taxonomic characters vary from 
specimen to specimen. When one first determines a species, he may 
be troubled by the variability of certain characters, but while identi- 
fying the species on numerous occasions, he gradually acquires what 
is known as a "habitus picture" ; that is, he recognizes the species with- 
out difficulty just as one would recognize a well-known human in- 
dividual. Even if one is positive that he knows a certain person, 
accurately describing him to someone else is usually very difficult or 
impossible. Likewise, a person may positively know a certain insect 
without being able to describe it. The surest method of recognizing 
a species of ant is to know definitely the characters that distinguish it. 



MANDIBLE 
CLYPEU5 
CARINA 
EYE 



FUNICULUS 
FRONTAL 
AREA 

SCAPE 



FRONTAL 
FURROW 



SPUR 
OCCIPUT 
COXA 



MEDIAN OCELLUS 
LATERAL OCELLUS 
VERTEX 
PROTHORAX 
MESOTHORAX 



ME50NOTAL CONSTRICTION 
TROCHANTER 
PETIOLE 



FEMUR 
TIBIA 



V 

METATARSUS 




Figure I. Fomica exsec/o/Wes Forel, Allegheny mound ant, dorsal view of worker 
showing anatomical structures. 



HOUSE-INFESTING ANTS OF THE EASTERN UNITED STATES 9 



KEY TO SUBFAMILIES OF FORMICIDAE 

(For the identification of workers, especially major workers or 

soldiers) 

1. Abdominal pedicel composed of two segments, the petiole and 

postpetiole (fig. 23). Sting present but not always visible 

externally 2 

Abdominal pedicel composed of a single segment, the petiole 
(fig. 1). Sting lacking 3 

2. Frontal carinae placed very close to each other, almost touch- 

ing, and not covering the antennal insertions. Antennae at- 
tached almost at the edge of the mouth. Eyes lacking or else 
extremely small, ocelluslike. Workers polymorphic. Three 

species Dorylinae Leach (p. 10). 

Frontal carinae not placed very close to each other (fig. 1) , each 
carina bearing a lobe that more or less conceals the antennal 
insertion. Antennae not attached, almost at the edge of 
the mouth. Eyes usually noticeably large and composed of 
a number of ommatidia. Workers monomorphic, dimorphic, 
or polymorphic. Twenty -three species. 

Myrmieinae Lepeletier (p. 10). 

3. Cloacal orifice terminal, circular, surrounded by a fringe of 

hairs \-{fig. 48, CO) . Antennal fossa not always touching the 
posterior border of the clypeus. Workers of many of the 
species capable of emitting either a formic acid, or a pleasant, 
lemon- verbena or citronella odor. Workers monomorphic or 
polymorphic. Eighteen species. 

Formicinae Lepeletier (p. 14) . 

Cloacal orifice ventral, transverse, slit-shaped, not surrounded 
by a fringe of hairs (fig. 31, CO). Antennal fossa touching 
the posterior border of the clypeus. Workers of most of the 
species capable of emitting a characteristic, disagreeable, rot- 
ten coconut or tapinoma odor. Workers monomorphic. 
Erect hairs extremely sparse or lacking on the dorsum of the 
thorax. Six species Dolichoderinae Forel (p. 13). 

1 The fringe of hairs may sometimes be partly or entirely worn away./ 



10 TECHNICAL BULLETIN 1326, U.S. DEPT. OF AGRICULTURE 

KEYS TO SPECIES 
Key to Species of Subfamily Dorylinae Leach 

1. A tooth between the base and apex of each tarsal claw (fig. 

2,b). The only U.S. species. 

Labidus coeous (Latreille) (p. 17). 

The tooth lacking between the base and apex of each tarsal 
claw 2 

2. Head densely sculptured, subopaque. Superior border of 

mandible, especially near its junction with the masticatory 
border of the mandible, convex (fig. 3, b) . 

Neivamyrmex nigrescens (Cresson) (p. 18) . 
Head sparsely sculptured, shiny. Superior border of man- 
dible not as described above (fig. 4, b) . 

Neivamyrmex opacithorax (Emery) (p. 19) . 

Key to Species of Subfamily Myrmicinae 

Lepeletier 

1. Antenna with 10 segments, the last two segments of the f unicu- 

lus enlarged and forming a distinct club. Clypeus longi- 
tudinally bicarinate. Epinotum unarmed 2 

Antenna with more than 10 segments 5 

2. Eye extremely small, usually composed of not more than 

4 to 6 ommatidia. Workers monomorphic, unusually small, 
1.5-2 mm. in length (fig. 23) . 

Solenopsis molesta (Say) (p. 43) 

Eye normal sized and competed of many ommatidia. Work- 
ers polymorphic, ranging in size from 1.6 to 6 mm 3 

3. Mandible strongly incurved. Anterior border of meso- 

pleuron irregular in outline, usually bearing one or more 
spines or teeth. Petiolar node narrow in profile. Head ex- 
traordinarily large, out of proportion to remainder of body 
(fig. 21, a, b) Solenopsis geminata (Fabricius) (p. 40). 
Mandible not strongly incurved. Anterior border of meso- 
pleuron regular in outline, lacking spines or teeth. Petiolar 
node not unusually narrow in profile 4 

4. Antennal scape short, when fully extended its apex reaching 

approximately half the distance between the eye and the 
posterior border of the head. Masticatory border of the 
mandible usually with three distinct teeth. Petiole com- 
monly with antero- ventral tooth (fig. 20, a, b). 

Solenopsis xyloni McCook (p. 38) . 

Antennal scape longer, when fully extended its apex reaching 
more than half the distance between the eye and the poste- 
rior border of the head. Masticatory border of mandible 
usually with four distinct teeth. Petiolar and postpetiolar 



HOUSE-INFESTING ANTS OF THE EASTERN UNITED STATES 11 

nodes, when viewed from above and behind, with apparent 
longitudinal impressions or grooves (fig. 22, a, b). Intro- 
duced species. Solenopsis saevissima richteri Forel (p. 41). 

5. Antenna with 11 segments 6 

Antenna with 12 segments 11 

6. Dorsal surface of thorax with three pairs of prominent 

spines. Legs extraordinarily long. Workers polymorphic, 
1.5-12 mm. in length (fig. 27) Atta texana (Buckley) 
(p. 50). 
Characters not as described above 7 

7. Gaster viewed from above not subcordate. Postpetiole not 

attached to dorsal surface of the base of the gaster. Frontal 
carina forming a partial groove or scrobe for the reception 
of the scape. Border of the eye nearest the mandible form- 
ing an acute angle ( fig. 26 ) . Introduced species. 

Wasmannia aurojnmctata (Eoger) (p. 48). 
Gaster subcordate when viewed from above. Postpetiole at- 
tached to dorsal surface of the base of the gaster. Frontal 
carina not forming a partial groove or scrooe for the recep- 
tion of the scape 8 

8. Antennal scape unusually short, scarcely attaining or barely 

surpassing the posterior border of the head. Epinotal 
spines remarkably short, much shorter than the distance 
between their bases, parallel and convex on the outer sides. 
Worker small and usually weakly sculptured (fig. 12,a). 

Grematog aster as hmeadi'M.&yr (p. 28). 
All characters not as described above 9 

9. Hairs coarse, 'bristlelike, rather numerous, and well distrib- 

uted on the thorax. Thoracic dorsum subopaque or 
opaque, coarsely rugose or striate (fig. 15,a) . 

Crematogaster lineolata (Say) (p. 32) . 

Hairs more slender and either confined to a small group on 
each shoulder of the pronotum or else in appearance mixed 
with suberect or erect pubescence 10 

10. Pubescence appressed. Thorax usually with only a few erect 

hairs. Dorsum of thorax with definite longitudinal striae 
or fine rugae (fig. 13). Crematogaster cerasi (Fitch) (p. 30). 
Pubescence usually suberect or erect on head and thorax only, 
never on gaster. Dorsum of thorax with fine punctures, 
but never with rugae (fig. 14) . 

Crematogaster eZaraMayr (p. 31). 

11. Epinotum unarmed. Clypeus usually bicarinate 12 

Epinotum armed. Clypeus not bicarinate 15 

12. Workers dimorphic. Posterior portion of head and also of 

epinotum transversely rugulose (fig. 19). Introduced 

species Monomorium destructor (Jerdon) (p. 37). 

Workers monomorphic. Posterior portion of head and also 
of epinotum not bearing transverse rugulae 13 



12 TECHNICAL BULLETIN 1326, U.S. DEPT. OF AGRICULTURE 

13. Thorax distinctly lighter in color than the head and gaster, 

which are normally dark brown or blackish (fig. 18). In- 
troduced species. .Monomoriumfloricola (Jerdon) (p. 36). 
Color not as described above 14 

14. Body uniform dark brown or black and largely smooth and 

shining (fig. 16). 

Mononwrivan minimum ( Buckley ) (p. 33 ) . 
Body light brown or yellowish to yellowish red except the 
posterior portion or the gaster. Head, thorax, petiole, and 
postpetiole finely punctulate, subopaque (fig. 17). Intro- 
duced species Monomoriumpharaonis (Linnaeus) (p. 34). 

15. Workers dimorphic. Head extraordinarily large in propor- 

tion to the size of the body. Length of body 1.5-3 mm. 

Antenna with a very distinct 3-segmented club 16 

Workers not dimorphic. Head not extraordinarily large in 
proportion to the size of the body 18 

16. Ventral surface of head in profile with a pair of distinct teeth 

or spines anteriorlj 7 . Mesonotum, in profile, with a trans- 
verse, steplike impression (fig. 11) . 

Pheidole dentata Mayr (p. 27) . 

Characters not as described above 17 

17. Head sculptured, subopaque, except for a small smooth and 

shiny area on or near the occipital border (fig. 10) . 

Pheidole floridana Emery (p. 26) . 

The posterior half of the head largely smooth and shiny. 
Body light to dark brown (fig. 9). 

Pheidole bicarinatavinelandica Forel (p. 25) . 

18. Posterior border of clypeus not forming a sharp, raised mar- 

gin in front of the antennal fossa. Slender ants with long 
legs and antennae. Length 3.5-7 mm. Antennae with in- 
distinct 4-segmented club .. 19 

Posterior border of clypeus forming a sharp, somewhat raised 
margin in front of the antennal fossa. Neither slender 
ants nor with unusually long legs and antennae. Length 
2.5-4 mm. Antennae with a 3-segmented club. Intro- 
duced species -. 22 

19. Lateral face of the frontal lobe bearing a flange which ex- 

tends posteriorly in the form of a tooth (fig. 5,b) . 

Aphaenog aster lamellidens Mayr (p. 20) . 
Lateral face of frontal lobe without a toothed flange _. . 20 

20. Postpetiolar node broader than long, suboval in shape. Epi- 

notal spines longer than the dorsal surface or base of the 
epinotum. Body almost devoid of erect hairs (fig. 7). 

Aphaenogaster tennesseensis (Mayr) (p. 23). 
Postpetiolar node not as described above. Epinotal spines 
shorter than the dorsal surface or base of the epinotum. 
Body with numerous erect hairs , 21 

21. Anterior border of mesonotum forming a strongly project- 

ing transverse welt or gibbosity, the gibbosity impressed 



HOUSE-INFESTING ANTS OF THE EASTERN UNITED STATES 13 

or concave in the center. Epinotal spines as long as, or 
longer than, the declivous surface of the epinotum, and di- 
rected upward (fig. 8, a, b) . 

Aphaenog 'aster /w^waKoger (p. 24). 

Anterior border of mesonotum not as described above. Epi- 
notal spines not as long as the declivous surface of the epi- 
notum (fig. 6) Aphaenog aster rudis (Emery) (p. 21). 

22. Head bearing a partial sulcus or groove for the reception of 
the antennal scape. Thorax reticulate-rugose. Head and 
thorax yellowish red or reddish (fig. 25). Introduced 

species Tetramorium quineense (Fabricius) (p. 47). 

Head not bearing a partial sulcus or groove for the reception 
of the antennal scape. Head and thorax longitudinally 
striated and dark brown or blackish (fig. 24). Introduced 
species Tetramorivan caespitum (Linnaeus) (p. 45). 

Key to Species of Subfamily Dolichoderinae 

Forel 

1. Dorsal surface of epinotum in the form of a prominent conical 

or tuberculate elevation posteriorly. Maxillary palpus un- 
usually long, the third segment approximately as long as the 
combined lengths of the fourth, fifth, and sixth segments. 
Ventral surface of head with a weakly developed psammo- 
phore. Mesonotum in profile with a perceptible angle an- 
terior to the mesoepinotal suture (fig. 30) . 

Dorymyrmex pyramicus (Roger) (p. 56). 
Characters not as described above .1 2 

2. Petiolar node vestigial ; when viewed from above, more or less 

hidden by the base of the gaster (fig. 31,a) 3 

Petiolar node not vestigial, suberect to erect, and usually easily 
seen in, profile : 4 

3. Body color rather uniform, either a light brown or black. 

Length 2.4-3.25 mm. (fig. 31,a). Tapinoma sessile (Say) 
(p. 57). 

Head dark, the thorax and gaster commonly with pale areas of 
variable size; legs, mouth parts, and antennae very pale. 
Length 1.3-1.5 mm. (fig. 32). Introduced species. 

Tapinoma melanocephalwm (Fabricius) (p. 59). 

4. Head subtriangular. Mandible with both teeth and fine 

denticulae. Thorax usually without erect hairs. Epinotum 
in profile, short, approximately twice as high as long. Body 
a uniform light brown or brown (fig. 28). Introduced 

species.: Iridomyrmex humilis (Mayr) (p. 52). 

Head subrectangular. Mandible with small or large teeth but 
no fine denticulae. Thorax usually with a few erect hairs 
on the pronotum or epinotum. Epinotum in profile not twice 
as high as long. (fig. 29) . 

Iridomyrmex pndnosus (Eoger) (p. 54). 



14 TECHNICAL BULLETIN 1326, U.S. DEPT. OF AGRICULTURE 

Key to Species of Subfamily Formicinae 

Lepeletier 

1. Antenna inserted at or very close to the posterior border of 

the clypeus. Workers monomorphic. Pronotum, in profile, 

not flattened 9 

Antenna inserted a considerable distance from the posterior 
border of the clypeus. Workers polymorphic. Large 
species, 4-12 mm. in length. Pronotum, in profile, usually 
flattened. Clypeal border and antennal fossa never touch- 
ing each other . 2 

2. Scapes and legs with abundant long, coarse, yellowish, sub- 

erect to erect hairs ; the hairs on the legs not arranged as a 
row of short, graduated bristles on the flexor surfaces of 
each middle and hind tibia (fig. 37) . 

Camponotus dbdomindlis flondamts (Buckley) (p. 69). 
All of the characters not as described above 3 

3. Anterior border of clypeus with a distinct narrow, median 

emargination or impression (fig. 38,b). Workers 4-9 mm. 

in length .. 4 

Anterior border of clypeus without a distinct narrow, median 
emargination or impression. Workeis 6-12 mm. in length- 6 

4. Cheeks and clypeus without elongate piligerous foveolae 5 

Cheeks and clypeus with elongate piligerous foveolae. Head, 

thorax, petiole and legs yellowish red or reddish (fig. 38,a) . 
Camponotus caryae discolor (Buckley) (p. 70). 

5. Body normally a uniform or almost uniform dark brown or 

black (fig. 39) Camponotus nearcticus Emery (p. 72). 

Body, exclusive of the gaster, yellowish red or reddish (fig. 
40) Camponotwrasilis'WheelGr (p. 73). 

6. Clypeus ecarinate or scarcely carinate. Head of major worker, 
excluding the mandibles, slightly broader than long. Cly- 
peal fossae well developed. Head and thorax subopaque 

or opaque 7 

Clypeus carinate. Head of major worker, excluding the man- 
dibles, as long as broad or longer than broad . 8 

7. Body blackish or black. Pubescence appressed, pale yellow 

or white, and noticeably long on the dorsal surface of the 
gaster (fig. 35) 

Camponotus pennsylvanicus (DeGeer) (p. 63). 

Posterior portion of the thorax, the petiole, legs, and base of 

the gaster yellowish red or reddish. Pubescence golden 

yellow and usually short on the dorsal surface of the gaster 

(fig. 36) Camponotm fen-ugineus (Fabricius) (p. 67). 

8. Head shiny. Middle and hind tibia each with a row of gradu- 

ated, erect, bristles on their flexor surface (fig. 33). 

Camponotus castaneus (Latreille) (p. 60). 



HOUSE-INFESTING ANTS OF THE EASTERN UNITED STATES 15 

Head subopaque. Middle and hind tibia each without a row 

of graduated, erect, bristles on their flexor surface (fig. 34). 

Oamponotustortviganus'Emery (p. 62). 

9. Eye located nearer to the base of the mandible than to the 

posterior border of the head 10 

Eye located nearer to the posterior border of the head than 
to the base of the mandible 11 

10. Antennae and legs extraordinarily long. Body slender and 

bearing long coarse, suberect to erect, grayish or whitish 
hairs ; the suberect to erect hairs normally absent from the 
scapes. Integument with a peculiar grayish-violaceous 
luster or sheen (fig. 41) . Introduced species. 

Paratrechinalongicornis (Latreille) (p. 74). 

Unlike alternative above in one or more characters. Scapes 

usually, and tibiae always, with coarse, suberect to erect 

hairs (fig. 42) ParatrecMna (Nylanderia) spp. (p. 76). 

11. Thorax with a strong constriction in the mesonotum, the con- 

striction somewhat subcylindrical. Scape extending ap- 
proximately one-half its length .beyond the posterior border 
of the head. Gaster from above, with the base meeting each 
side in a distinct angle (fig. 43) . 

Prenolepis imparts (Say) (p. 78). 
Differing from the above in one or more characters 12 

12. Maxillary palpus short, 3-segmented. Eye unusually small 

to small. Body hairs commonly barbed. 1 Workers capa- 
ble of emitting pleasant lemon-verbena or citronella odors__ 13 
Maxillary palpus long, 6-segmented. Eye normal. Body 
hairs not barbed. Workers capable of emitting distinct 
formic acid odors 16 

13. Petiolar node, in profile, with a narrow and rather sharp 

summit (fig. 48,a) 14 

Petiolar node, in profile, with a thicker, blunt summit (fig. 
49) 15 

14. Antennal scape when fully extended with its apex consider- 

ably surpassing the posterior border of the head. A small 
tooth on the superior border of the mandible near the junc- 
tion of the mandible's superior and masticatory border 
(fig. 48, b) . Erect hairs on the dorsal surface of the gaster 
largely confined to a transverse row on the posterior border 
of each segment (fig. 48, a) . 

Acanthomyops inter jectus (Mayr) (p. 88). 
Antennal scape when fully extended with its apex either not 
attaining or else not surpassing the posterior border of the 
head. The small tooth lacking on the superior border of 
the mandible as described for interjectus. Dorsal surface 
of gaster with widely distributed, abundant, erect hairs (fig. 
47) Acanthomyops claviger (Roger) (p. 86). 

1 It may be difficult to see the barbs on the hairs except under high magnification : not 
less than 61.2. 

749-356 O 65 2 



16 TECHNICAL BULLETIN 1326, U.S. DEPT. OF AGRICULTURE 

15. Cheeks with a number of long, erect hairs. Dorsal surface of 

gaster with numerous long, erect hairs. Scapes and f uniculi 
strongly thickened from base to apex (fig. 50) . 

Acanthomyopslatipes (Walsh) (p. 91). 

Cheeks lacking erect hairs. Dorsal surface of thorax and 
gaster with short, erect, hairs. Scapes and funiculi per- 
ceptibly but not strongly thickened from base to apex 
(fig. 49) ________ Acanthomyops murphyi (Forel) (p. 89). 

16. Terminal segments of the maxillary palpus successively and 

gradually decreasing in length toward the apex of the 
palpus. Petiole in profile with a narrow and thin summit, 
the dorsal border usually with a very distinct emargina- 
tion. Dorsal surface of gaster bearing abundant short, 
suberect hairs of approximately the same length (fig. 
46) ---------------- Lasius wmbratus (Nylander) (p. 84). 

Terminal segments of the maxillary palpus rather long and 
of approximately the same length __ '. _____________________ 17 

17. Antennal scapes and tibiae with numerous suberect or erect 

hairs. Penultimate basal tooth of mandible markedly re- 
duced in size relative to the two flanking teeth; or the gap 
between the penultimate and terminal basal teeth tends to 
be larger in area than the terminal basal tooth and variable 
in shape. Color light brown to medium brown, rarely dark 
brown. Anterior border of the median clypeal lobe obtusely 
angular (fig. 45) __________ Lasius neoniger Emery (p. 81). 

Antennal scapes and tibiae either without suberect or erect 
hairs or usually with less than 10 each. Penultimate and 
terminal basal teeth subequal in size, and the gap between 
them of about the same area as the terminal tooth and con- 
stant in shape. Body color brown, to very dark brown, or 
approaching blackish. Anterior border of the median cly- 
peal lobe forming an even, broad, parabolic curve (fig. 



44) __________________ Lasiv, alienus (Foerster) (p. 80 



g. 
). 



HOUSE-INFESTING ANTS OF 1HE EASTERN UNITED STATES 17 

DISCUSSION OF THE SPECIES 

Labidus coccus (Latreille) 

This is a native and widely distributed species, ranging from Okla- 
homa and Arkansas to Texas and Louisiana, and south to Argentina. 

Taxonomic Characters 

Subfamily and generic characters: Polymorphic. Antenna ex- 
tremely short, 12-segmented. Frontal carinae placed extremely close 
to each other, not concealing antennal insertions. Clypeus remarkably 
short, almost lacking. Eye absent or extremely small, ocelluslike. 
Epinotum unarmed. Tarsal claw with a tooth between its base and 
apex. Abdominal pedicel composed of two segments, the petiole and 
postpetiole. Sting present, but not always exserted. Specific char- 
acters: Workers 2.9-9.7 mm. long. Scape short, scarcely attaining 
more than mid length of head. Petiole with an anteroventral protu- 
berance or spine. Most of body smooth and shiny except posterior half 
or more of thorax. Body color castaneous to reddish brown. 

Biology and Economic Importance 

This legionary ant lives in more or less temporary nests in decayed 
logs and stumps, or in the ground beneath stones and other objects. 
The ant may also nest beneath basement floors, or in and around foun- 
dation walls. Colonies are exceedingly large, containing many thou- 
sands of individuals. Workers are light-avoiding and are not often 
seen. Natural foods are arthropods, small mammals, and birds, which 
the ants kill and eat as carrion or refuse. Nuts and foods of a high 
protein content form much of their diet. The ants may invade houses 
in search of the latter foods, or meat. They can kill chickens and small 
pets, and also bite and sting fiercely. The species has also been known 
to short-circuit telephone wires by removing the lead sheathing. How- 
ever, the ants are predators of many injurious insects such as the 




Figure 2. Labidus coccus (Latreille): or, Lateral view of worker; b, lateral view of tarsal 

claw showing tooth. 



18 TECHNICAL BULLETIN 1326, U.S. DEPT. OF AGRICULTURE 

third-stage larva of the secondary screw-worm CaUitroga macellaria 
(Fabricius) . 

References: Wheeler and Long, 1901, p. 159; Wheeler, 1908b, pp. 408-409; 
Wheeler, 1926, p. 264; Lindquist, 1942, pp. 850-852; Creighton, 1950, pp. 61-62; 
Enzmann, 1951, pp. 449-450 ; Borgmeier, 1955, pp. 91-93, figs. ; Hess, 1958, pp. 
35-37. 

Neivamyrmex nigrescens (Cresson) 

This is a native species which ranges from Nebraska and Virginia 
south to California and Florida, thence into Mexico. It is the most 
common and widely distributed species of Neivamyrmex in the United 
States. 

Taxonomic Characters 

Subfamily and generic characters: Polymorphic. Antenna rather 
short, stout, 12-segmented. Eye extremely small, ocelluslike. Frontal 
carinae placed extremely close to each other, not covering antennal 
insertions. Clypeus extremely short, almost lacking. Epinotum un- 
armed. Tarsal claw lacking a tooth between its base and apex. 
Abdominal pedicel composed of two segments, the petiole and post- 
petiole. Sting present but not always exserted. Specific characters : 
Workers 2.8-5.8 mm. long. Apex of scape noticeaoly surpassing an 
imaginary line connecting posterior borders of eyes. Superior border 
of mandible meeting masticatory border of the mandible in a rounded 
outline or convexity (fig. 3,b). Body, exclusive of gaster, opaque, the 
surface largely covered with dense, granular punctures interspersed 
with coarse foveolae, the foveolae especially apparent on dorsum of 
head and thorax. Body color highly variable, from light brown 
through dark reddish brown to almost black. 

Biology and Economic Importance 

This species has temporary nesting sites similar to those of Labidus 
coecus. On a number of occasions I have received specimens from 
houses under conditions indicating the ants may have been nesting 
beneath the basement floor or in and around the foundation walls. 




Figure 3. Neiyamyrmex nigrescent (Cresion): o, Lateral view of worker; t, right mandible 
showing the convex superior border. 



HOUSE-INFESTING ANTS OF THE EASTERN UNITED STATES 19 

Schneirla estimates that very large colonies may contain as many as 
150,000 to 250,000 workers. As far as known, each colony has only 
one functional or mother queen. New colonies are formed by a split- 
ting process in which a daughter queen leaves the parental nest, accom- 
panied by a number of workers. A mature colony is capable of pro- 
ducing a small number of females, some of which may be fertilized 
in the nest by their brothers, but this does not preclude mating outside 
the nest, or with males of other colonies. Since females are never 
winged, they can make no nuptial flight. The functional queen in a 
colony is not capable of taking care of her brood a task delegated 
to the workers. Males have emerged from nests from September into 
November. Workers are less light-avoiding than those of coecus; in 
fact, many of their foraging activities take place in daylight. The 
natural food of these ants is not well known but random observations 
indicate they are highly predacious on other insects such as beetles, 
termites, and the adults and brood of other ants. Newell reports the 
species as an important predator on the Argentine ant. Workers fre- 
quently seek meat for food in houses and stores. The presence of ants 
(workers or males, or both) in a house can be very annoying to a 
housekeeper, who frequently mistakes the males for termites or other 
insects. On several occasions I have received specimens of workers of 
N. fallax Borgmeier and N. pilosus mexicanus (F. Smith) that had 
fallen into crude, unprotected country wells in localities in the Gulf 
Coast States, causing the water to have a foul odor and an unpleasant 
taste. Although neither nigrescens nor any of the other legionary ants 
treated in this paper have been received from such situations, it would 
not be surprising if they were found under these circumstances. 

References: Wheeler, 1900, pp. 563-574; Wheeler and Long, 1901, pp. 170-172; 
Newell, 1914, p. 147; Wheeler, 1926, pp. 263-266; Smith, 1927, pp. 401-404; Cole, 
1940, p. 38; Smith, 1942, pp. 537-539, fig-; Creighton, 1950, pp. 64-66, fig.; 
Borgmeier, 1955, pp. 498-500, figs. ; Schneirla, 1958, pp. 215-255. 

Neivamyrmex opacitkorax (Emery) 

N. opacithoraaa is a native species that ranges from Kansas to Vir- 
ginia, south to California and Florida, thence into Mexico (Baja 
California) and Costa Rica. 




Figure 4. A/e/Vomyrmex opacithora* (Emery): o, Lateral view of worker; 6, right mandible 
showing the non convex superior border. 



20 TECHNICAL BULLETIN 1326, U.S. DEPT. OF AGRICULTURE 

Taxonomic Characters 

/Subfamily and generic characters: Same as for nigrescens. Spe- 
cific characters: Workers 2.2-4.6 mm. long. Similar to nigrescens 
except antenna apparently not so stout, scape not quite as long, nor 
eye as distinct. Superior border of mandible with a straight (at 
least not convex) margin between basal tooth and masticatory border 
(fig. 4,b). Color usually lighter, ranging from light to dark reddish 
brown ; thorax usually the darkest, legs and gaster lighter than head 
and petiole. Sculpture noticeably different from that of nigrescens; 
in the latter species, head, thorax, petiole, and postpetiole are densely 
sculptured and opaque, whereas in opacithoraoe only the thorax and 
petiole are densely sculptured and opaque. 

Biology and Economic Importance 

This species so closely resembles nigrescens in biology and economic 
importance that only a few additional comments are necessary. N. 
opacithorax is apparently less common in the Eastern United States 
than nigrescens. The two species are similar in that males of each 
emerge from nests during September to November. The following 
notes on opamthorax, indicating that the ants may infest houses from 
nests outdoors, were sent in by a correspondent in Kansas City, Mo., 
about September 10, with several males and associated workers. He 
wrote as follows concerning them: "My own attention was first at- 
tracted to them when some few of them got into our living room, com- 
ing up from beneath the fireplace, and the next day into an adjoining 
room, coming this time from a cold air register, each time being noticed 
almost immediately and disposed of by spraying. Further search dis- 
closed the fact that they entered the basement through a small hole or 
two in the foundation wall about which they swarmed. ... I have 
seen nothing more of any winged ones. There are several armies of 
ants which have been working between unknown places and the rock 
foundation of our home. They enter small cracks from the outside. 
These might be the same species." 

References: Wheeler and Long, 1901, p. 163; Wheeler, 1908b, p. 411; Smith, 
1942, p. 560, fig. ; Borgmeier, 1955, pp. 504-506, figs. ; Schneirla, 1958, pp. 214-255. 

Aphaenogaster lamellidens Mayr 

This is a native species ranging from Illinois to New York and 
south to Louisiana and Florida.. 

Taxonomic Characters 

Subfamily and generic characters: Body slender, with long legs 
and antennae. Antenna 12-segmented, with an indistinct 4-segmented 
club. Frontal carinae not placed close to each other, partly conceal- 
ing the antennal insertions. Eye well developed and with numerous 
ommatidia. Promesonotal and mesoepinotal sutures well defined. 
Epinotum armed with a pair of prominent spines. Abdominal pedicel 
composed of two segments, the petiole and postpetiole. Petiole dis- 
tinctly pedunculate. Gaster from above oval, without truncate base. 
Specific characters: Workers 4.1-6.5 mm. long. Distinguished from 
the other species of Aphaenogaster by the following characters : Outer 
face of frontal lobe bearing a flange which projects rearward in the 



HOUSE-INFESTING ANTS OF THE EASTERN UNITED STATES 21 




Figure 5. Aphaenogaster lamellidens Mayr: a, Lateral view of worker; b, frontal lobe 
showing the highly characteristic flange which terminates posteriorly in a tooth. 

form of a tooth (fig. 5, b) ; epinotal spines shorter than base of 
epinotum; head, thorax, petiole, and posfcpetiole reddish, the gaster 
yellowish ; usually the scapes, femora, and tibiae are dark or blackish. 
The most dependable character for distinguishing the species is the 
peculiar flange of the frontal lobe. As mentioned under tennesseensw, 
that species and lamellidens are somewhat similar, although the re- 
semblance is only superficial. However, the thoracic sculpture of 
lamellidens is less coarse, especially on the sides of the thorax. 

Biology and Economic Importance 

This species, which appears to be more common in the southern 
section of its range than elsewhere, typically nests in wood. It forms 
colonies of a few hundred to several thousand individuals in stumps 
and logs that vary from fairly well preserved to well decayed. Dennis 
states that lamellidens is a highly adaptable form that nests in open 
or shady situations and in dry-to-moist habitats. He thinks it is the 
most common species of Aphaenogaster in Tennessee, but he has never 
found it above 2,500 feet. Wheeler claims to have found females 
starting incipient colonies in sand, but no other observers appear to 
have confirmed this observation. Dennis reports a nest in the brick 
chimney of a house. I have received specimens of workers said to 
have emerged from grooves in the floor boards of a home, the grooves 
apparently having been made by the ants or other insects. The species 
is similar to fulva in general feeding habits and economic importance. 

References: Wheeler, 1905b, p. 383; Dennis, 1938, pp. 285, 304; Cole, 1940, 
p. 52 ; Van Pelt, 1958, p. 13. 

Aphaenogaster rudis (Emery) 

A. rudis is a native species, which ranges from Illinois to Massa- 
chusetts and south to Colorado and Florida. This ant appears in our 
earlier literature under the name A. fulwa aquia (Buckley). 



22 TECHNICAL BULLETIN 1326, U.S. DEJ>T. OF AGRICULTURE 




Figure 6. Aphacnogasfer radii (Emery), lateral view of worker. 

Taxonomic Characters 

Subfamily and generic characters: Same as for jtamellidens. Spe- 
cific characters: Workers 4.5-5 mm. long. Frontal lobe not bearing 
a flange which, projects posteriorly in the form of a tooth as figured 
for lamellidens. Head varying in sculpture from longitudinally 
rugulose-reticulate (especially anterior portion) to mainly punctate. 
Pronotum varying from punctuate to transversely rugulose, more 
commonly punctate. Anterior border of mesonotum not in the form 
of a transverse welt or gibbosity that is cleft or impressed in the 
center, as described and figured for fulva. Epinotal spines short, 
seldom as long as basal half of epinotum. Erect hairs present on 
most of dorsal surface of body in contrast to tennesseensw. Body 
color light brown to brown, with antennae and legs usually lighter. 

Biology and Economic Importance 

A very common and highly adaptable species. The ants may nest 
in exposed soil or under stones, logs, in decaying wood, leaf litter, 
hollow stems of plants, or under the bark at the base of trees. Nests 
occur in open fields and open and dense woods up to altitudes of at 
least 5,000 feet. The species is especially a woodland-nesting form. 
Colonies are seldom large, usually ranging from less than a hundred 
to several thousand individuals, one of the largest recorded having 
approximately 3,500 individuals. Population studies by Headley and 
Talbot showed that although most colonies contained only a single 
wingless female, a number had 2, 3, 4, or as many as 15 females. 
Fusion of colonies, in some instances, may account for the large num- 
ber of females. The immature stages of this species pass the winter 



as eggs and larvae. Males and winged females reach maturity hi 
late July, apparently from overwintering larvae. Headley found that 
nests excavated in the ground were composed of one to four galleries, 
ranging in length from 1 to 34 inches deep, from which 2 to 17 cham- 
bers radiated. This species is a host of the temporary ant parasite A. 



HOUSE-INFESTING ANTS OF THE EASTERN UNITED STATES 23 

tennesseensis. The natural food of rudis is insects (which they kill or 
eat as refuse), seeds, and the pollen of ground-nesting bees. Headley 
was able to trace workers to their nest by feeding them bread crumbs. 
A. rudis is quite similar to fulva in its economic habits and importance. 

References: Hendrickson, 1930, pp. 78-79; Dennis, 1938, pp. 286-287, 305; 
Wesson and Wesson, 1940, pp. 90, 94; Headley, 1943, p. 25; Headley, 1949, pp. 
265-272 ; Talbot, 1951, pp. 302-307 ; Talbot, 1957, pp. 377-379. 

Aphaenogaster tennesseensis (Mayr) 

This is a native species, which ranges from South Dakota and On- 
tario, south to Oklahoma and Georgia. It is not only one of the most 
striking forms of Aphaenogaster, out one of the most easily recog- 
nized. 

Taxonomic Characters 

Subfamily and generic characters: Same as for lamellidens. Speci- 
fic characters: Workers 4.1-5.3 mm. long. A. tennesseensis may be dis- 
tinguished from the other species of Aphaenogaster by the following 
characters: Strongly protuberant mesonotum (especially anterior por- 
tion) ; a pair of extraordinarily large epinotal spines noticeably 
thickened at the base, very acute apically, and longer than the base of 
the epinotum (best seen from above) ; the peculiarly shaped post- 
petiolar node which, when seen from above, is slightly broader than 
long and definitely broader posteriorly than anteriorly; the coarse 
thoracic sculpture, much of which is reticulate-rugose ; the almost com- 
plete absence of erect hairs on the dorsal surface of the body; the 
sparse, appressed pubescence; and the body color (the head, thorax, 
petiole, and postpetiole reddish, the gaster yellowish, and the append- 
ages dark) . The species bears a superficial resemblance to lamellidens. 




Figure 7. Aphacnogastzr rennesseens/s (Mayr), lateral view oi worker. 



24 TECHNICAL BULLETIN 1326, U.S. DEPT. OF AGRICULTURE 

Biology and Economic Importance 

No complete biological studies have been made on tennesseensis. 
During its early stages of colony formation, this species is probably 
a temporary parasite in the ground nests of A. rudis and A. rudis 
picea (Emery). Both A. rudis and rudis picea have similar habits, 
and most commonly nest in the soil ; picea, however, seems to occur 
at high altitudes. Indicative of this are the small size of the female, 
her highly polished body, and very large epinotal spines, and the 
peculiar fact that tennesseensis lives in ground nests only when its 
females occur in the nests of rudis and picea. Otherwise, the species 
is exclusively a wood-nesting ant, found typically in wooded areas. 
The ants live in decaying logs and stumps, or in decayed spots in both 
live and dead trees. Van Pelt has found this species to be rare in the 
Blue Ridge Mountains at altitudes from 4,100 to 4,500 feet. Colonies 
vary from a few hundred to several thousand individuals. The spe- 
cies appears to be more common in the northern section of its range. 
Its feeding habits and economic importance are quite similar to those 
of fulva. 

References: Wheeler, 1905b, pp. 373, 383 ; Gaige, 1914, pp. 3-5, 11-13 ; Wheeler, 
1926, pp. 114, 447-448, 450; Dennis, 1938, pp. 287-288, 305; Gregg, 1944, pp. 
456, 465 ; Van Pelt, 1963, p. 212, 

Aphaenogaster fulva Roger 

This native species ranges from Nebraska to Vermont south to 
Colorado and Florida. 

Taxonomic Characters 

/Subfamily and generic characters: Same as for lamellidens. 
Specific characters: Workers 3.5-5.8 mm. long. A. fulva is distin- 
guished from the other species of Aphaenogaster by the shape of the 




Figure 8. Aphaenogaster fulva Roger: o, Lateral view of worker; fc, posterodorsal view of 
the strongly projecting anterior border of the mesonotum which is cleft or impressed in 
the center. 



HOUSE-INFESTING ANTS OF THE EASTERN UNITED STATES 25 

anterior border of the mesonotum, which forms a strongly projecting 
transverse welt or gibbosity cleft, or is impressed in the center (fig. 8, 
b) ; and by epinotal spines, which are highly characteristic in being un- 
usually long and acute, as long as or longer than the declivous face 
of the epinotum, and with their apices directed considerably upward. 
The general body color is usually light brown to dark brown, the 
gaster and appendages often being darker. 

Biology and Economic Importance 

This species nests in small- to moderate-size colonies in rotting wood, 
such as logs or stumps, and in the soil beneath stones and other objects. 
It is very characteristically found in wooded areas, but also shows a 
high adaptability to various types of ecological habitats. Van Pelt 
reports occasional colonies of this species in the Blue Kidge Mountains 
at altitudes of from 3,500 to 4,500 feet. The natural food of fulva is 
live and dead insects. Workers are not known to seek or eat honeydew. 
The ants have been found nesting in the soil around the base of houses 
and in the rotting wood of houses. Although workers infest houses, I 
have only one record of their infesting household foods ; that was pea- 
nut butter. Probably they will show a preference for meat or food 
with a high protein content. The species does not appear to be a house 
pest of any major importance. 

References: Wheeler, 1905b, pp. 373, 383; Wheeler, 1916, pp. 585-586; Wheeler, 
1926, pp. 81, 83, 206, 448, 453 ; Dennis, 1938, pp. 285-286 ; Headley, 1943, p. 25 ; Van 
Pelt, 1958, pp. 12-13 ; Van Pelt, 1963, p. 212. 

Pheidole bicarinata vinelandica Fore! 

This is a native species, which ranges from Nebraska to New York 
and south to Arizona and Florida. 

Taxonomic Characters 

Subfamily and generic characters: Dimorphic. Head extraordi- 
narily large in proportion to body, with prominent occipital lobes and 
a frontal furrow. Antenna 12-segmented, with a distinct 3-segmented 




Figure 9. Pheidole bicarinata vintlandica Forel, lateral view of worker. 



26 TECHNICAL BULLETIN 1326, "U.S. DEPT. OF AGRICULTURE 

club. Frontal carinae not placed close to each other, partly concealing 
antennal insertions. Abdominal pedicel of two segments, the petiole 
and postpetiole. Petiole pedunculate. Postpetiolar node frequently 
angulate or conical on the sides. Specific characters : Workers 1.6-3 
mm. long. Head subrectangular, longer than broad, bilobed, and 
with a median furrow. Scape short, extending approximately to mid- 
length of head. Middle of anterior border of clypeus emarginate. An- 
terior half of head largely longitudinally rugulose; posterior half, 
smooth and shiny. Thorax with prominent humeral angles. Post- 
petiolar node distinctly broader than long, laterally angulate. Body 
color yellowish or light brown to darker brown. 

Biology and Economic Importance 

These ants, a common and widely distributed species of Pheidole, 
form small- to moderate-size colonies in rotting wood, and also nest in 
exposed soil, or under the cover of objects. Nests are commonly con- 
structed in open areas, or where the ground is covered with grass and 
weeds. The species is highly adaptable, living in deserts, on mountains, 
beaches, and in many other situations. Nests may occur at altitudes 
ranging from a few feet to at least 6,000 feet. The natural food is 
honeydew, seeds, and small insects. Vickery records workers trans- 
porting individuals of the corn root aphid Anuraphis maidiradicis 
(Forbes) from plant to plant in cottonfields. Workers have been 
known to feed on meats, greases, and breads in houses. The species 
is an intermediate host of the tapeworm of wild and domesticated tur- 
keys, Raillietina georgiensis Reid and Nugara, of the chicken tape- 
worm R. echinobothnda (Megnin), and of the domestic fowl tape- 
worm/?, tetragona (Molin). 

References: Wheeler, 1904, p. 301; Wheeler, 1906a, pp. 336-337; Vickery, 1910, 
pp. 102, 105, 116 ; Gaige, 1914, pp. 5-7 ; Horsfall, 1938, pp. 409-421 ; Dennis, 1938, 
pp. 282, 304 ; Cole, 1940, p. 42 ; Reid and Nugara, 1961, pp. 885-889. 

Pheidole fioridana Emery 

A native species, fioridana ranges from North Carolina to Florida 
and through the Gulf Coast States to Texas. 

Taxonomic Characters 

Subfamily and generic characters : Same as for bicarinata vineland- 
ica. Specific characters : Workers 1.5-2.6 mm. long. Anterior border 
of clypeus with a median emargination. Clypeus with a median longi- 
tudinal carina, on each side of which a few smaller, longitudinal rug- 
ulae are present. Head bilobed and with a frontal furrow. Scape 
short, extending to about midlength of head. Frontal carinae about 
length of scapes, distinctly widening posteriorly and forming a partial 
scrobe for the reception of each scape, and with a flattened or depressed 
area to the side of, and posterior to, the scape. Head largely punctu- 
late, subopaque except for a smooth and shiny area of variable size 
that may include the posterior third or fourth of the head,, or only a 
narrow, transverse band on the occipital lobes. Thorax with distinct 
humeral angles. Postpetiolar node distinctly wider than long and 
angulate or conical laterally. Body color yellowish or very light 
brown. 



HOUSE-INFESTING ANTS OF THE EASTERN UNITED STATES 27 




Figure 10. fheidole floridana Emery, lateral view of worker. 



Biology and Economic Importance 

This species, the least common of the three Pheidoles discussed in 
this paper, appears to be confined largely, if not entirely, to the coastal 
area, where the ants construct nests in the exposed soil or under the 
cover of objects; they also nest in logs and stumps, in or under litter, 
and at the base of trees. Van Pelt reports the species occurring in 
and around houses in the Welaka Reserve of Florida, and attracted 
to grease and peanut butter ; we have received reports of their nesting 
in a chimney. Although collecting seeds is a common habit of ants 
in the genus Pheidole, no information is available as to whether the 
ants feed on honeydew or gather the seeds of weeds and grasses for 
food, but workers are said to feed on the germinating seed of long 
leaf pines. 

References: Smith, 1930, p. 3 ; Van Pelt, 1958, pp. 16-17. . 

Pheidole dentata Mayr 

This native species ranges from Kansas and Virginia south to Texas 
and Florida. 

Taxonomic Characters 

Subfamily and generic characters : Same as for bicarinata mneland- 
ica. Specific characters: Workers 2.4^3.8 mm. long. Head bilobed 
and with a median furrow. Anterior border of clypeiis with a median 
emargination. Scape extending very noticeably past midlength of 
head. Anterior half of head sculptured, opaque ; posterior half smooth 
and shiny. Ventral surface of head with a pair of prominent teeth or 
spines on anterior border (best seen in profile) . Much of the meso- 
notum in the form of a transverse step-like process (best seen in pro- 
file) . Postpetiolar node very distinctly broader than long, and sub- 
angular on each side. Sides of thorax, excluding those of prothorax, 
sculptured, subopaque. Dorsal surface of gaster with erect hairs of 



28 TECHNICAL BULLETIN 1326, U.S. DEPT. OF AGRICULTURE 




Figure II. Pheidole dentata Mayr, lateral view of worker. 

variable length, some unusually long. Body color light brown to dark 
brown. 

Biology and Economic Importance 

This is an especially common species of Pheidole in the Southern 
States. The ants form small to large colonies in the exposed soil or 
under the cover of objects such as stones, logs, wood, or debris; they 
also nest in rotting wood. Their natural food is largely live and dead 
insects, seeds, and honeydew. Vickery found that workers of dentata 
have the same relation to Anuraphis maidiradicis (Forbes) in cotton- 
fields as do workers of bicarinata vinelandica. This ant is probably 
an intermediate host of the domestic fowl tapeworm Raillietina tetra- 
gona (Molin) since workers have been seen to carry gravid segments 
of the tapeworm into their nest. In houses, the ants are known to 
feed on meats, grease, liver, molasses, peanut butter, and fruit juices ; 
it is believed that they have a preference for high-protein foods. 

References: Vickery, 1910, pp. 102, 105, 116; Mitchell and Pierce, 1912, p. 71; 
Dennis, 1938, pp. 281, 304 ; Case and Ackert, 1940, pp. 393-395 ; Cole, 1940, p. 44 ; 
Hess, 1958, pp. 31-32, 55-59, 62-64; Van Pelt, 1958, pp. 14-15. 

Crematogaster ashmeadi Mayr 

A native species, which ranges from Texas east to Virginia and 
Florida. It is a strictly southern or southeastern species. 

Taxonomic Characters 

/Subfamily and generic characters : Monomorphic. Head subquad- 
rate or subrectangular. Antenna 11-segmented, with a 3-segmented 
club. Frontal carinae placed far apart, subparallel, partly concealing 
antennal insertions. Thorax short, stout. Mesoepinotal region with 
a pronounced constriction. Epinotum with a pair of spines of variable 
size and shape. Abdominal pedicel of two segments, the petiole and 
postpetiole. Petiole trapezoidal, broadest anteriorly (fig. 12,&). 
Postpetiole dorsally with a longitudinal impression or furrow, which 



HOUSE-INFESTING ANTS OF THE EASTERN UNITED STATES 29 




Figure 12. Cremofogorfer ashmtadi Mayr: a. Lateral view of worker; b, dorsal view of 

netiole. 



forms two more or less distinct hemispheres (fig. 15,6). Postpetiole 
attached to dorsal surface of base of gaster. (raster subcordate, more 
convex ventrally than dorsally, and with an acute apex. Sting present 
but not always exserted. /Specific characters: Workers 2.6-3.2 mm. 
long. Head largely shiny except for sculpture on frontal carinae, 
cheeks, and clypeus. Scape short, its apex scarcely attaining, or barely 
surpassing, the posterior border of the head. Dorsal surface of thorax 
so finely sculptured as to appear rather smooth and shiny in most 
lights. Side of thorax distinctly punctulate; subopaque on meso- 
metapleuron. Mesonotum slightly impressed anteriorly on each side, 
subtruncate posteriorly, with a median longitudinal carina on its disc. 
Epinotal spines normally shorter than distance between base of spines, 
the spines much thickened basally, subparallel, acute apically. Erect 
hairs sparse on body, especially thorax. Pubescence on body sparse, 
closely appressed. Body color highly variable, that of head and 
thorax ranging from light reddish brown through brown to black. 

Biology and Economic Importance 

This ant is largely arboreal, nesting in cavities in plants and trees, 
insect galls, and logs and stumps. Colonies are apparently small to 
moderate in size. Workers tend honeydew-excreting insects, but also 
feed on both dead and live insects. The ants frequently nest in the 
woodwork of houses, in rafters, shingles, and posts. They damage in- 
sulating board and hard fiberboard, and remove the rubber insula- 
tion from telephone wires, causing short circuits. In houses, the ants 
seem to be omnivorous, but may show a slight preference for meats 
and sweets. Experimental tests by Smith and Weiss have shown that 
this ant can transmit Azalea flower spot, Orulinia azaleae Weiss. 

References: Smith, 1924, pp. 79-80; Wheeler, 1932, p. 7; Cole, 1940, p. 46; 
Smith and Weiss, 1942, p. 42 ; Van Pelt, 1958, pp. 21-22. 



30 TECHNICAL BULLETIN 1326, U.S. DEPT. OF AGRICULTURE 




figure 13. Crematogasttr cerasi (Fitch), lateral view of worker. 

Crematoffoster cerasi (Fitch) 

A native species, which ranges f r6m southern Canada through the 
eastern Rocky Mountains to New Mexico and east through the Black 
Hills to the Ozarks and Georgia. It is occasionally called the cherry 
ant. This species has been frequently confused with other species 
of Crematog aster, especially lineolata. 

Taxonomic Characters 

S^ family and generic characters : Same as for ashmeadi. Specific 
characters: Workers 2.6-4 mm. long. Scape when fully extended 
usually noticeably surpassing posterior border of head. Promeso- 
notum subopaque, bearing fine longitudinal striae or rugulae, the 
sculpture from some aspects or in certain lights, however, appearing to 
be finely punctulate. Mesonotum with a median carina (best seen in 
profile) . Mesoepinotal impression usually strongly defined. Epinptal 
spines divergent, long and acute, straight or occasionally curved. Sides 
of thorax sculptured, subopaque. Erect hairs on thorax normally con- 
fined to a small cluster on each pronotal shoulder. Body pubescence 
closely appressed. Head and thorax varying from reddish brown to 
dark brown or almost black. 

Biology and Economic Importance 

0. cerasi nests in small-to-large colonies in the ground beneath ob- 
jects, and in rotting stumps and logs, branches, and empty nuts on the 
surface of the soil. Nests occur hi diverse habitats such as open fields, 
pastures, marshes, and woods. Van Pelt reports the species as occur- 
ring in the Blue Ridge Mountains in occasional colonies at altitudes 
from 5,100 to 5,500 feet, and rarely from 5,600 to 6,000 feet. Workers 
in large colonies are aggressive and emit a repulsive odor. They tend 
honeydew-excreting insects, and feed on both live and dead insects. 
Winged forms commonly emerge from their nests from late June to 
mid November. C. cerasi appears to be the most common house-inf est- 
ing form of Crematogaster, at least in Virginia and Maryland. The 



HOUSE-INFESTING ANTS OF THE EASTERN UNITED STATES 31 

ants have been found in various parts of houses such as the roof, siding, 
ceiling, and porch, but most commonly in and around door and 
window frames, where any caste or combination of castes may appear. 
Some correspondents insist that the ants have done appreciable damage 
to the woodwork, but others maintain they can detect no damage. In 
some instances the ants seem to occupy, and perhaps enlarge, pre- 
formed cavities in the wood made by other insects. Although the 
ants feed on various household foods, I have no definite information 
on their food preferences. On one occasion specimens were reported 
to have caused a short circuit in an electric transformer by removing 
the insulation. This ant may be an intermediate host of the poultry 
tapeworm Raillietina tetragona (Molin) ; worker ants have been seen 
carrying gravid tapeworm segments into their nest. 

References: Gaige, 1914, pp. 3-4, 8-9 ; Talbot, 1934, p. 420 ; Case and Ackert, 
1940, pp. 393-395; Amstutz, 1943, p. 168; Wheeler and Wheeler, 1944, p. 245; 
Gregg, 1944, pp. 456, 462 ; Talbot, 1957, pp. 376-378, 381 ; Kannowski, 1959, pp. 125, 
157 ; Van Pelt, 1963, p. 212. 

Crematogaster clara Mayr 

This native species ranges from Indiana to New Jersey and south 
to Texas and Florida. It is common in the lower Mississippi Valley. 
In earlier literature the species has been recorded erroneously as 
laeviuscula Mayr. 

Taxonomic Characters 

Subfamily and generic characters: Same as for ashmeadi. Specific 
characters : Workers 3.3-4 mm. long. Scape rather long when fully 
extended, usually noticeably surpassing posterior border of head. 
Head shiny except for the areas dulled by the sculpturing on cheeks 
and clypeus. Mesonotum with median carina. Mesoepinotal im- 
pression well defined. Dorsum of thorax (promesonotum) with very 
fine sculpture", largely punctulatipns ; the area subopaque or shiny, 
especially when viewed with varying brightness or direction of light. 
Side of thorax sculptured and subopaque except for that of prothorax, 




Figure 14. Cremo/ogos/er clara Mayr, lateral view of worker. 
749-356 O J65 3 



32 TECHNICAL BULLETIN 1326, U.S. DEPT. OF AGRICULTURE 

which is smooth and shiny. Epinotal spines long and divergent, 
straight or occasionally curved, acute apically. Pubescence long, sub- 
erect, and relatively dense, at least on head and thorax ; admixed with 
long erect hairs, especially on head and anterior part of thorax. Body 
color varying from a yellowish or very light brown through brown to 
blackish. 

Biology and Economic Importance 

The ants nest in moderate to large colonies in cane stems, branches, 
trees, and rotton stumps and logs. Buren, in unpublished data, says 
favorite habitats are flatwoods, swamps, and marshes. As in most 
species of Crematogaster, workers feed largely on honeydew and the 
flesh of live and dead insects. The ants are known to nest in the wood- 
work of houses, and to infest household foods. Like ashmeadi,. they 
are almost omnivorous but seem to show a slight preference for sweets 
and meat. They can cause short circuits in telephone wires by remov- 
ing the rubber insulation. Workers have been reported to have killed 
newly hatched birds. 

References: Smith, 1924, p. 80; Dennis, 1938, pp. 272, 274, 283, 304; Cole, 1940, 
pp. 29, 47. 

Crematogaster lineolata (Say) 

This species occurs in southern Canada and ranges south along the 
Rocky Mountains and east to Florida. It has sometimes been called 
the lined acrobatic ant. Various species of Crematogaster have been 
misdetermined as lineolata in our earlier literature. 

Taxonomic Characters 

Subfamily and generic characters: Same as for ashmeadi. Specific 
characters: Workers 2.5-3.5 mm. long. Occiput and vertex or head 
occasionally puntulate, subopaque. Scape when fully extended notice- 
ably surpassing posterior border of head. Dorsum of thorax sub- 




Figure 1 5. Cr ematogasftr lineolata (Say): a, Lateral view of worker; 6, posterodorsol view 

of poitpetiole. 



HOUSE-INFESTING ANTS OF THE EASTERN UNITED STATES 33 

opaque or opaque; promesonotum typically roughly sculptured, bear- 
ing coarse longitudinal rugae or striae, interspersed with punctures. 
Sides of thorax sculptured, subopaque. Erect hairs on dorsum of 
thorax coarse or bristlelike, moderately numerous, and rather well 
distributed. Mesonotum with median carina. Mesoepinotal impres- 
sion well defined. Epinotal spines normally rather long and diver- 
gent, straight or occasionally curved. Pubescence short and closely 
appressed. Body color ranging from light brown through dark brown 
to blackish. This common and widely distributed species can be read- 
ily distinguished by its pilosity, pubescence, and sculpture. 

Biology and Economic Importance 

This species nests in moderately large to large colonies in exposed 
soil or under stones and other objects, and in logs, stumps, and dead 
trees. Van Pelt records the species nesting in the Blue Bidge Moun- 
tains in occasional colonies at altitudes of 3,500 to 5,500 feet. Work- 
ers feed largely on honeydew obtained from honeydew-excreting in- 
sects, and on live and dead insects. They have been recorded as 
predators of winged termites, the immature stages of the cotton boll 
weevil, grape curculio, and codling moth. When alarmed, workers 
bite fiercely, and give off a repulsive odor. Males and winged females 
have been observed in the nest or emerging from the nest from mid 
June to late September. Like other species of Crematogaster, lineolata 
nests in the woodwork of houses, and also infests household foods. 
Although largely omnivorous, lineolata seems to show a slight pref- 
erence for sweets and meats, or foods of a high protein content. The 
ants sometimes occupy the nests of wood-nesting wasps. 

References: Wheeler, 1905b, pp. 378-379; Wheeler, 1906b, pp. 1-18; Davis and 
Bequaert, 1922, p. 8; Dennis, 1938, p. 282; Cole, 1940, pp. 29, 46-47; Wesson and 
Wesson, 1940, p. 93 ; Van Pelt, 1963, p. 212. 

Monomorium minimum (Buckley) 

Little black ant. This is a native species, which ranges throughout 
southeastern Canada and the northern and eastern sections of the 
United States. Its range in western North America has not yet been 
accurately delimited. In our literature, this species was formerly and 
incorrectly called minutum Mayr, or a subspecies of minutwn. 

Taxonomic Characters 

/Subfamily and generic characters: Monomorphic. Head distinctly 
longer than broad. Antenna 12-segmented, with well-defined, 3-seg- 
mented club. Frontal carinae short, not close together, partly con- 
cealing the antennal insertions. Clypeus with a pair of longitudinal 
carinae which are often extended beyond the anterior margin of the 
clypeus as more or less distinct teeth. Prothorax with rounded 
humeri. Promesonotal suture absent or obsolescent. Mesoepinotal 
region with well-defined constriction. Epinotum unarmed. Abdom- 
inal pedicel composed of two segments, the petiole and postpetiole. 
(raster usually with distinct basal angles (best seen from above). 
Sting present but not always exserted. Specific characters : Workers 
1.5-2 mm. long. Body almost entirely smooth and shiny except for 



34 TECHNICAL BULLETIN 1326, U.S. DEPT. OF AGRICULTURE 




Figure 16. Monomer/urn minimum (Buckley), little black ant, lateral view of worker. 

some weak sculpturing on cheeks, anterior border of head, and meso- 
metapleuron. Body dark brown to blackj typically black. Body 
pubescence sparse, closely appressed, most evident on dorsum of gaster. 

Biology and Economic Importance 

M. minim/wm is one of the most common and best known of our house- 
infesting ants, but no detailed biological work has been done on the 
species. Under natural conditions the ants are highly adaptive in 
their nesting and feeding habits. They may nest in exposed soil or 
under cover of objects and in rotting or faulty wood. Van Pelt has 
found colonies of this ant rare in the Blue Ridge Mountains at altitudes 
of 4,100 to 5,000 feet. Colonies are generally moderate to large in size, 
and contain numerous fertile females. Males and winged females have 
been recorded from June to August. Workers are predacious and car- 
nivorous on other insects, tend plant lice or other honeydew-excreting 
insects, visit floral and extrafloral nectaries of plants, and may even 
feed on the pollen in flowers of certain plants. The ants may invade 
houses from outdoors, or nest in the woodwork or masonry of the 
building. Because they are small, the ants are not capable of doing 
any appreciable damage to building materials. Workers feed on a 
wide variety of household foods such as sweets, meats, bread, grease, 
oils, cornmeal, fruits, and fruit juices. I have received reports of 
recently hatched bluebirds and kingfishers being killed by these ants. 

References: Marlatt, 1898, p. 3, fig.; Dennis, 1938, pp. 271-272, 274, 279-280; 
Metcalf and Flint, 1939, p. 770 : Cole, 1940, pp. 14, 29, 40 ; Gregg, 1944, pp. 454, 456, 
466 ; Smith, 1950, p. 281 ; Hess, 1958, pp. 26-27, 55-60, 62, 63 ; Van Pelt, 1963, p. 
212. 

Monomorium pharaonis (Linnaeus) 

Pharaoh ant. An introduced species which is thought to be native 
to the African Region. The ant has been widely distributed to all 
parts of the world by commerce. It is one of the most common and best 
known of all house-infesting ants. The Pharaoh ant probably occurs 
in every town or city of commercial importance in the United States. 
Although not widely or uniformly distributed in such localities, it is 



HOUSE-INFESTING ANTS OF THE EASTERN UNITED STATES 35 




Figure 17. Monomorium pharaonis (Linnaeus), Pharaoh ant, lateral view of worker. 



especially common in hotels, large apartment houses, groceries, or 
other places where food is commercially handled. It is believed that 
on numerous occasions in our earlier literature the Pharaoh ant was 
confused with the thief ant Solenopsis molesta. 

Taxonomic Characters 

Subfamily and generic characters: Same as for minimum,. /Specific 
characters : Workers monomorphic, approximately 2 mm. long. Each 
segment of antennal club gradually increasing in size toward the apex 
of club. Clypeal carinae rather weakly defined. Pair of teeth on the 
anterior border of clypeus absent or obsolescent. Eye comparatively 
small, with approximately 6-8 ommatidia in its greatest diameter. 
Prothorax with subangular shoulders. Thorax with well-defined 
mesoepinotal impression. Erect hairs on body sparse. Pubescence of 
body sparse, closely appressed. Head, thorax, petiole, and postpetiole 
densely but weakly punctulate, dull, or subopaque ; the clypeus, gaster, 
and mandibles shiny. Body color ranging from yellowish or light 
brown to reddish. Gaster with varying amounts of infuscation, which 
is confined largely to apical portion. 

Biology and Economic Importance 

The ants normally nest in inaccessible places in buildings, where they 
undoubtedly breed continuously the year around, and produce pro- 
digious numbers of individuals. For instance, in 2 years on his prem- 
ises, Bellevoye captured 1,360,000 workers, 1,809 wingless females, 94 
winged females, and 560 males. These figures do not account for the 
innumerable individuals he was unable to trap. Home owners have 
been known to consider selling their houses because of the ravages of 
this pest. A ship owner is known to have lost a great deal of time and 
spent $4,000 in trying to eradicate these ants from his ship. Approxi- 
mately 38 days are required for the development of the worker from 
egg to adult and 42 days for the development of the male and female. 
In houses, the ants often nest in such odd places as between sheets of 
stationery, layers of linens, and other abnormal places. In one in- 
stance, a person returning from an extended trip to the Canal Zone 
found a colony between clothing in his trunk. Practically omnivorous, 



36 TECHHICAL BULLETIN 1326, U.S. DEPT. OF AGRICULTUEE 

the ants are known to feed on jelly, sugar, syrup, and other sweets, 
cakes and breads, pies, butter, liver, and bacon. They seem to have a 
preference for grease, fats, and meats. Workers feed on both dead and 
live insects. Very often they appreciably damage insect collections by 
feeding on dried specimens. Keports have been received of ants gnaw- 
ing holes in silk, rayon, and rubber goods. The Pharoah ant is with- 
out doubt the most persistent and difficult of all our house-infesting 
ants to control or eradicate. The success of this species is probably 
due to their many reproductive females, their ability to breed the 
year around, their accessibility to an unlimited amount of food, and to 
the fact that females do not have to expose themselves to the elements 
or enemies by traveling great distances to find suitable nesting sites. 
Numerous daughter colonies apparently are produced by a splitting 
or budding process from an original mother colony, since no nuptial 
nights have been observed. A spread of many miles would therefore 
have to be accomplished by man. Those especially interested in the 
biology and control of this species should consult Peacock et al. (1950) . 

References: Bellevoye, 1889, pp. 230-233; Marlatt, 1898, pp. 1-2 fig.; Herrick, 
1914, pp. 173-176, fig. ; Donisthorpe, 1927, pp. 103-109, fig. ; Smith, 1934, pp. 139- 
149; Metcalf and Flint, 1939, p. 770; Peacock and Baxter, 1950, pp. 171-178; 
Peacock, Hall, Smith, and Goodfellow, 1950, pp. 1-50; Sudd, 1953, pp. 17-18. 

Monomorium fioricola (Jerdon) 

This is an introduced species whose original home appears to be the 
African or Oriental Region, probably the latter. It is now established 
in a number of localities in Alabama and Florida, especially the latter 
State. 

Taxonomic Characters 

Subfamily and generic characters : Same as for minimum. Specific 
characters: Workers 1.4-1.8 mm. long. Body unusually slender. 
Clypeal teeth apparently absent or obsolescent. Gaster much nar- 
rowed basally (best seen from above) . Body largely smooth and shiny 
except for sculpturing on cheeks, clypeus, and mesometapleuron. 
Body hairs and pubescence sparse ; pubescence appressed, scarcely dis- 
cernible. Body strikingly bicolored, head and gaster dark brown or 




Figure 18. Monomorium flon'co/o (Jerdon), lateral view of worker. 



HOUSE-INFESTING ANTS OF THE EASTERN UNITED STATES 37 

blackish, and thorax, petiole, postpetiple, and appendages noticeably 
lighter. The worker of floricola is easily distinguished from the other 
species of Monomorium by its unusually slender and very strikingly 
bicolored body. 

Biology and Economic Importance 

Under normal conditions ftoricola appears to be largely, if not ex- 
clusively, an arboreal species^ nesting in twigs and branches or under 
the bark of trees and other plants. It may nest in dead as well as live 
wood. Colonies are of diverse size, but are frequently large. As 
with destructor, there are numerous fertile females, but they differ 
from females of most species in not ever having borne wings. Workers 
visit the floral and extrafloral nectaries of plants, tend honeydew- 
excreting insects, and feed on insects, many of which they doubtlessly 
kill. In Puerto Rico this is one of the most important ants associated 
with the pineapple mealybug Pseudococcus brevipes (Ckll.) . The ants 
commonly infest houses and feed on household foods, but little is 
known about their food preferences except that on occasions they have 
eaten sugar and fed on fountain syrup in drug stores. I do not know 
whether the ants invade houses from outdoors or nest in the house, but 
they are probably capable of both. However, their small size pre- 
vents them from doing any appreciable damage to woodwork or 
masonry. 

References: Wheeler, 1905a. pp. 87-88; Marlatt, 1916, p. 3; Wheeler, 1924, 
p. 108 ; Smith, 1936, pp. 833-834 ; Plank and Smith, 1940, pp. 59-60, 63. 

Monomorium destructor ( Jerdon) 

This is an introduced species, the original home of which is prob- 
ably the Oriental Region. The species is established in Tennessee and 
especially in a number of localities in Florida. 

Taxonomic Characters 

Subfamily and generic characters: Same as for minimum with the 
following exceptions : Workers variable in size, somewhat dimorphic. 




Figure 19. Monomorium destructor (Jerdon), lateral view of worker. 



38 TECHNICAL BULLETIN 1326, U.S. DEPT. OF AGRICULTURE 

Head in larger individuals proportionally broader with respect to 
length. First two segments of antennal club subequal. Clypeal 
carinae and clypeal teeth absent or obsolescent. Specific characters: 
Workers 1.8-3.0 mm. long. Dorsal surface of posterior border of 
head and dorsal surface of epinotum with fine transverse rugulae. 
Mesopleuron and side of epinotum sculptured, remainder of body 
largely smooth and shiny. Body hairs sparse, widely distributed, 
long and slender, suberect to erect. Body color pale yellowish or very 
light brown, with gaster noticeably inf uscated, this mfuscation vary- 
ing in degree and extent. 

Biology and Economic Importance 

M. destructor lives in large colonies containing many fertile females. 
The ants nest in the soil or in buildings, depending largely upon 
whether they occur in tropical, semitropical, or temperate regions. 
Workers are highly predacious on other insects but also tend honey- 
dew-excreting insects and feed on seeds. They move slowly in single 
file and appear to follow the trail by scent. The ants are a common 
and important house-infesting form. They are almost omnivorous 
and feed on such household foods as cookies, sweets, breads, meats, oils, 
greases, and animal substances. They gnaw holes in fabrics and rub- 
ber goods, and remove the rubber insulation from electric or telephone 
wires. (On one occasion they were reported to have apparently dam- 
aged exposed polyethylene cable by gnawing into it.) People are 
reported to have been bitten or stung fiercely while in bed. One in- 
vestigator found bubonic plague bacteria in the feces of ants that had 
fed on plague-infected rats. 

References: Wroughton, 1892to, p. 186 ; Wheeler, 1906c, pp. 23-24 ; Marlatt, 1916, 
p. 3; Clarke, 1922, pp. 329-333; Wheeler, 1926, pp. 10, 153, 221; Smith, 1936, 
p. 839; Kalshoven, 1937, pp. 65-71; O'Kourke, 1956, pp. 109-110; Kempf, 1960, 
pp. 506-507. 

Solenopsis xyloni McCook 

Southern fire ant. This native species ranges from California to 
South Carolina (southern part) and Florida (northwest corner) . It 
is especially common in some of the Gulf Coast States. S. xyloni has 
been confused with the fire ant Solenopsis geminata (Fabncrus) on 
many occasions. 

Taxonomic Characters 

Subfamily and generic characters : Polymorphic. Antenna 10-seg- 
mented, with 2-segmented club. Eye well-developed and with numer- 
ous ommatidia. Frontal carinae far apart, partly concealing antennal 
insertions. Clypeus bicarinate, the anterior border with 2 to 5 teeth. 
Masticatory border of mandible with 3 to 4 well-defined teeth. Meso- 
epinotal region of thorax with well-developed suture or impression. 
Epinotum unarmed. Abdominal pedicel composed of two segments, 
the petiole and postpetiole. Sting present but not always exserted. 
Much or most of body smooth and shiny. Specific characters: Work- 
ers 1.6-5.8 mm. long. Head not extraordinarily large, as with geminata 
(p. 40) , distinctly less than twice as broad as pronotum. Mandible not 
as strongly incurved as that of geminata. Masticatory border of man- 



HOUSE-INFESTING ANTS OF THE EASTERN UNITED STATES 39 




Figure 20. So/enops/'s xyloni MeCook, southern fire ant: a. Lateral _vie,w of worker; b, right 
mandible showing shape of mandible and number and arrangement of teeth. 

dible with three well-developed teeth (fig. 20, b), often a fourth or 
vestigial tooth posterior to the well-developed teeth. Antennal scape 
short, apex of scape, when fully extended, reaching about half way 
between eye and posterior border of head. Anterior border of meso- 
pleuron continuous, without toothlike or other irregularities. Petiolar 
node, in profile, not sharp or bladelike at the summit as in geminata. 
Petiole usually with a distinct anteroventral tooth. Surface of meso- 
pleuron very finely sculptured, scarcely subopaque. Body, especially 
gaster, usually very hairy. Body color varying from yellowish to 
reddish, with gaster dark, especially around the posterior border of the 
gastric segments. 

Biology and Economic Importance 

8. xyloni is largely a ground-nesting species, the colonies of which 
may be freely exposed or under the cover of stones and other objects. 
The ants also nest in wood, sometimes even in the woodwork or ma- 
sonry of houses. Colonies are frequently very populous. Outdoors, 
the earth is commonly thrown from the nest in irregular and variable- 
sized, crater-shaped masses of loose soil. Workers are slow-moving 
when compared with such agile and quick-moving ants as the Argen- 
tine ant Iridomyrmex Jvumilis (Mayr). They are very sensitive to 
vibrations or jars, however, and when one steps on a nest, the workers 
rush out and viciously sting one's feet or legs. A complete study has 
not yet been made of the biology of xyloni. On numerous occasions 
recently fertilized females have been seen establishing nests independ- 
ently in the soil. The large population of some colonies suggests, how- 
ever, that more than one female takes part in reproductive activities. 
The ants are practically omnivorous, feeding on seeds, honeydew, flesh, 
the juices or sap of fruits and plants, and various human foods. The 
ants are especially known for their predacious habits, although they 
will also eat dead insects. Especially in the Gulf States and California, 
xyloni is one of the worst of the ant pests. The species affects man in 



40 TECHNICAL BULLETIN 1326, U.S. DEPT. OF AGRICULTURE 

many ways. It builds ugly mounds on lawns ; stings painfully, affect- 
ing individuals in different ways according to their degree of allergy 
(a small infant is reported to have been stung to death by the ants) ; 
steals seeds from seed beds; kills young or newly hatched poultry, 
quail, and other birds ; girdles nursery stock, such as citrus and pecans ; 
gnaws into the buds of okra and althea, and into potato tubers, dahlia 
stems, strawberry fruits, and the fruit of egg plants; bites holes in 
various fabrics such as woolens, silks, linen, and nylon; removes rub- 
ber insulation from around telephone wires and fouls telephone equip- 
ment with extraneous material; tends honeydew-excreting insects, and 
feeds on household foods such as nuts, cereals, cookies, butter, grease, 
meats, and fruits. These ants are especially fond of food with a high 
protein content. 

References: Smith 1936, pp. 120-122; Eckert and Mallis, 1937, pp. 19-21, figs.; 
Mallis, 1938, pp. 89-91; Eagleson, 1940, p. 700; Smith, 1950, pp. 271-272; Hess, 
1958, pp. 58-59 ; Blum, Roberts, and Novak, 1961, pp. 73-74. 

Solenopsis geminata (Fabricius) 

Fire ant. A native species which ranges from Texas to South Caro- 
lina and Florida and south to at least Costa Eica. It also occurs in the 
West Indies. The species occurs in most, if not all, of Florida and 
ranges inland in other States at distances varying up to as much as 
150 miles. The species has frequently been confused with xyloni. 
The name, "tropical fire ant" seems much more descriptive than that 
adopted by the Entomological Society of America. 

Taxonomic Characters 

Subfamily and generic characters: Same as for xyloni. Specific 
characters: Workers 2.4-6 mm. long. Head extraordinarily enlarged, 
more than twice as broad as pronotum, strongly bilobed posteriorly. 
Mandible sharply curved inward or "bowed" (fig. 21, b) , the mastica- 
tory border frequently toothless. Anterior border of mesopleuron 




Figure 21. So/enops/'s geminata (Fabricius), fire ant: a. Lateral view of worker; b, right 
mandible showing shape of mandible and the almost toothless condition of the masticatory 
border. 



HOUSE-INFESTING ANTS OP THE EASTERN UNITED STATES 41 

normally with toothlike or other irregularities. Thorax commonly 
sculptured and opaque on mesopleuron and side of epinotum, this 
sculpturing sometimes extending onto dorsum of epinotum. Petiolar 
node narrow in profile, especially dorsally, where it is somewhat 
bladelike. Color so highly variable as to defy accurate description; 
some individuals largely yellowish or light redish, others largely 
blackish, yet others with a mingling of light and dark colors. Species 
readily distinguished by the extraordinarily large head ; strongly in- 
curved and often toothless mandible; narrow petiolar node with sharp 
bladelike summit (in profile) ; and anterior border of mesopleuron, 
which is usually irregular in outline with spines or other projections. 

Biology and Economic Importance 

This species closely resembles S. xyloni in biology and economic im- 
portance. Until the introduction of the imported fire ant into Florida, 
geminata was not only the most common but the worst fire ant pest 
m that State. /S. geminata usually nests in the ground, from which 
it throws out earth in irregular piles, some of which may be as large 
as a bushel basket. The piles are commonly constructed around 
clumps of vegetation. The species may also nest in the soil under 
objects or in rotting wood. The ants usually nest in open areas in dry 
to moist soil of variable composition. Although no detailed studies 
have been made on the biology of this species, observations to date 
suggest possibly no more than one reproductive female per nest. 
.Males and females have been seen making nuptial flights from late 
May to early June. Colonies are frequently populous. The fire ant 
is especially noted for its predacious habits. Experiments conducted 
in Puerto Rico have shown that up to 91 percent of pupae of flies 
such as Musca domestica (Linnaeus), Gallitroga macellaria (Fabri- 
cius) , and Sarcophaga spp. have been destroyed by the fire ant and 
other ants. The fire ant is considered to be one of the most important 
predators of all the ants. It has been shown experimentally that 
workers of the fire ant can carry viable germs of dysentery on their 
bodies for at least 24 hours. This species affects man in ways almost 
identical to those of xyloni and its food preferences are quite similar. 
These ants have been reported to gnaw holes in rubber surgical gloves. 

References: Wheeler, 1914, pp. 164-465; Clark, 1931, p. 5; Smith, 1936, pp. 
838-839; Travis, 1941, pp. 15-22; Lindquist, 1942 pp. 850-852; Griffitts, 1942, 
pp. 271-272 ; Pimentel, 1955, pp. 28-30. 

Solenopsis saevissima richteri Forel 

Imported fire ant. This form has been introduced from South 
America, probably Argentina; richteri is a subspecies of saevissima 
(F. Sm.), a smooth, shiny, yellowish ant whose native home is also 
South America. It was first officially recorded in the United States 
from Mobile, Ala., in 1930, but apparently had been present there for 
at least 10 to 12 years. Infestations of various extent are now present 
in the Southern States from North Carolina and Florida west to 
Arkansas, Louisiana, and Texas, exclusive of Tennessee. There is 
no question that man has played an important role in the spread of 
this ant by his commercial activities. As hitch hikers, the ants have 



42 TECHNICAL BULLETIN 1326, U.S. DEPT. OF AGRICULTURE 




Figure 22. So/enops/'s soev/ss/'mo richteri Forel. imported fire ant: a. Lateral view of worker; 
t, right mandible showing shape of mandible ar\d number and arrangement of teeth. 

been carried by trucks, trains, and private cars. They have also 
been spread by shipments of nursery stock, building materials, logs, 
stumps, and soil. Their spread by flight, crawling, or by heavy rain 
storms is apparently of less significance. 

Taxonomic Characters 

Subfamily and generic characters: Same as for xyloni. Specific 
characters: Worker 2.8-6 mm. long. Head not remarkably large, dis- 
tinctly less than twice as broad as pronotum. Mandible not sharply 
curved inward or bowed as in geminata, masticatory border with four 
well-defined teeth (fig. 22,b). Apex of scape extending more than 
half the distance between upper border of eye and posterior border of 
head. Anterior border of mesopleuron continuous, not bearing teeth 
or irregular projections. Mesopleuron and side of epinotum with 
sculpture dense enough to appear subopaque. Dorsal surface of peti- 
olar and postpetiolar nodes, when viewed from above and behind, 
bearing apparent longitudinal furrows or foveolae. Typical species 
with deep piceous brown or blackish body except for a broad band of 
yellowish red at base of gaster. Non-typical form varying so widely 
in color as to defy accurate description ; in general, red and black pre- 
dominate and are usually intermingled. Reddish color most com- 
monly covers the body except much of the gaster, which is blackish. 
Non-typical form is by far the most common. 

Biology and Economic Importance 

The complete biology of richteri is unknown. The ants usually nest 
in the soil in open areas, less frequently in wooded areas in or around 
stumps and logs. Nests may be constructed in various types of soil 
ranging from loose to compact and varying greatly in the amount 
of moisture. In open areas, the earth is usually thrown from the nests 
in piles ranging from a few inches to as much as 3 feet or more in 
height. The larger mounds are generally dome-shaped or conical. 
The mound contains numerous galleries and chambers, both above 
and below the soil level. The ants frequently abandon one nest site 



HOUSE-INFESTING ANTS OF THE EASTERN UNITED STATES 43 

to seek another. Fully mature colonies may contain thousands of 
ants, including males and winged females. Due to the size of some 
colonies it is assumed that they contain more than one reproductive 
female. One -observer reports that he has found 23 wingless (or 
apparently fertile) females in a colony. 

In the Gulf coast area, males and winged females can be found in 
numerous nests almost any month of the year. Nuptial flights, how- 
ever, commonly take place in the spring out have also been observed 
from late December to late February. The ants occasionally nest in 
houses. Workers are almost omnivorous, feeding on the flesh of 
insects, birds, mammals, the sap or juices of plants and fruits, seeds, 
honeydew, and household foods such as meat, butter, cheese, peanut 
butter, nuts, breads, bacon, and grease. They seem to show a prefer- 
ence for foods of a high protein content. The ants are not only carniv- 
orous but highly predaceous. Nests are often constructed on lawns, 
disfiguring them and interfering with mowing. Paved sidewalks and 
public roads are sometimes undermined by the nests of the ants. 
Workers are highly aggressive and sting viciously; people allergic to 
their stings can suffer great discomfort or even death. The ants steal 
seeds from seedbeds and feed on the germinating seed of corn, causing 
a high percentage of loss. Workers are known to gnaw holes in 
fabrics, especially if soiled. They tend or may foster honeydew- 
excreting insects such as plant lice, mealybugs, and scales. They are 
known to kill young rabbits, pigs, and other mammals, and cniail and 
other birds are especially vulnerable to the ants at hatching time. 
The ants are often so abundant in gardens and fields that the gathering 
of vegetables and other crops is almost impossible. The ants gnaw 
into the roots, stems, buds, and fruit of plants such as cabbages, col- 
lards, okra, eggplant, and field peas. Young plants are seriously 
damaged by girdling or the removal of outer bark from roots or 
stems; young citrus stock is especially subject to this kind of attack. 

References: Creighton, 1930, pp. 88-89; Lyle and Fortune, 1948, pp. 833-834; 
Green, 1952, pp. 592-597 ; Anonymous, 1954, pp. 1-8, fig. ; Jung and Derbes, 1957, 
pp. 372-373; Caro, Derbes, and Jung, 1957, pp. 475-488, figs.; Anonymous, 1958, 
pp. 1-21, flgs. ; Favorite, 1958, pp. 445-448; Blum, Roberts, and Novak, 1961, 

-. TO f?A 



PP 

pp. 73-74. 



Solenopsis molesta (Say) 



Thief ant. A native species, which ranges through the eastern and 
central United States from southern Canada to the Gulf Coast. It is 
one of the smallest species discussed in this paper. The name "thief 
ant" refers to the habit of nesting in or very near the nests of other 
ants, which they rob of food and brood. At times this species has 
been confused with the Pharaoh ant; the two species, however, differ 
in many characters, some of which are easily recognizable. 

Taxonomic Characters 

Subfamily and generic characters : Same as for xyloni with the fol- 
lowing exceptions : Workers monomorphic. Eye minute, with 4^6 om- 
matidia or less. Specific characters: Workers extremely small, 1.3-1.8 
mm. long. Scape extending more than half the distance between eye 
and posterior border of head. Antennal club unusually large and 
elongate, approximately one and one-third times the combined lengths 



44 TECHNICAL BULLETIN 1326, U.S. DEPT. OF AGRICULTURE 




Figure 23. So/enops/'s moles fa (Say), thief ant, lateral view of worker. 

of remainder of f uniculus. Anterior border of clypeus with two dis- 
tinct teeth, the lateral tooth absent or obsolescent. Mandible normally 
with four teeth. Dorsal surface of head with sparse, scattered pili- 
gerous punctures which are apparently absent from a median area ex- 
tending from clypeus to posterior border of head ; punctures distinct 
in some kinds of lighting and indistinct in others. Postpetiolar node 
(viewed from above) wider than long, widest near the middle of its 
length. Body hairs moderately abundant and well distributed, sub- 
erect to erect, rather long. Body largely smooth and shiny. Body 
color ranging from yellowish or light brown to dark brown. 

Biology and Economic Importance 

S. molesta is one of our well-known and common species of house- 
infesting ants. Colonies contain many hundreds to a few thousand 
individuals. The ants nest in exposed soil or under cover of stones and 
other objects, in rotting wood, and in the woodwork and masonry of 
houses. Van Pelt has found colonies of this ant common in the Blue 
Ridge Mountains at altitudes of 3,500 to 5,500 feet. Nuptial flights 
have been observed from late July to early fall ; the sexed forms copu- 
late in flight. A single fertile female is capable of establishing her 
nest alone but she may not always do so ; one observer noted a nuptial 
flight in which some females carried at least one worker each attached 
to her body. Workers are almost omnivorous. They feed on both 
dead and live insects and are especially noted for being predaceous. 
They are also highly graniyorous and feed on planted or germinating 
corn, milo, sorghum, feterita, and kafir, often causing considerable 
damage to these crops. Workers are fond of honeydew and are known 
to tend plant lice, mealybugs, and scale insects. They feed on many 
household foods such as meats, breads, sweets, ripened fruits, animal 
fats, vegetable oils, nuts, and dairy products. They appear to prefer 
foods with a high protein content. In most instances the ants nest in 
houses, commonly in hot weather. In some homes they may give 
trouble periodically over a long period of years but in others they ap- 
pear only infrequently. I once found the ants nesting in a rotten porch 
floor near a kitchen, which they were invading to feed on crackers 



HOUSE-INFESTING ANTS OF THE EASTERN UNITED STATES 



45 



with a high fat content. The ants are a great annoyance to house- 
keepers because of their extremely small size, which allows them to 
enter containers not accessible to larger ants. The workers are well 
adapted for infesting cabinets, shelves, and containers, and often do 
so. even though the housekeeper has been unusually careful to keep 
everything closed and scrupulously clean. Unverified reports indi- 
cate that females may bite or sting people in bed at night. This species 
may be an intermediate host of the poultry tapeworm Railtietina 
tetragona (Molin) ; worker ants have been seen carrying gravid seg- 
ments of the tapeworm into their nest. 

References: McColloch and Hayes, 1916, pp. 23-38 ; Hayes, 1920, pp. 1-54, figs. ; 
Metcalf and Flint, 1939, pp. 389, 770; Case and Ackert, 1940, pp. 393-395; Mac- 
Namara, 1945, p. 40 ; Smith, 1950, p. 269 ; Van Pelt, 1963, p. 212. 

Tetramorium caespitum (Linnaeus) 

Pavement ant. This introduced species was undoubtedly brought 
into the United States by the early colonists from Europe. The ants 
are most common in cities and towns of the Atlantic Seaboard States, 
but are more sparsely distributed inland except in large centers of 
commerce, such as Cincinnati and St. Louis. Although not primarily 
an urban species, caespitum is confined largely to metropolitan areas 
in the United States. In Washington, D.C., and its metropolitan area, 
the species is not only one of the most common, but probably the pre- 
dominant, house-infesting ant. 

Taxonomic Characters 

Subfamily and generic characters: Monomorphic. Head subquad- 
rate or subrectangular, with emarginate posterior border. Frontal 
carinae placed far apart but partly concealing antennal insertions. 
Antenna 12-segmented, with 3-segmented club. Posterior border of 
clypeus forming a sharp ridge or rim in front of antennal fossa. Pro- 
notum (viewed from aoove) with angular shoulders. Promesonotal 
suture absent or obsolescent. Epinotum with a pair of spines of 




Figure 24. Tetramorium caespitum (Linnaeus), pavement ant, lateral view of worker. 



46 TECHNICAL BULLETIN 1326, U.S. DEPT. OF AGRICULTURE 

variable length. Metasternum extended posteriorly on each size to 
form a distinct spine or rounded lamella. Femora noticeably enlarged. 
Abdominal pedicel composed of two segments, the petiole and post- 
petiole. Sting present but not always exserted. Specific characters : 
Workers approximately 2.5-3 mm. in length. Apex of scape lacking 
more than its greatest width of attaining posterior border of head. 
Frontal carinae placed far apart, the distance between them widening 

gosteriorly, not forming scrobes for the reception of antennal scapes, 
lypeus with a prominent median carina and with a number of less 
distinct lateral carinae. Mesoepinotal suture forming a strongly de- 
fined constriction both laterally and dorsally on thorax. Femora and 
tibiae noticeably enlarged. Epinotum with a pair of very short spines 
or tubercles. Postpetiolar node (viewed from above) distinctly wider 
than long. Dorsal surface of head and much of dorsal surface of 
thorax with definite longitudinal striae. Body hairs fairly abundant, 
slender, suberect to erect, most of them rather long. Body color rang- 
ing from light brown through brown to blackish, the appendages 
lighter. 

Biology and Economic Importance 

No comprehensive study has yet been made of the biology of 
caespitum in the United States, although it is a common house and 
garden pest. Nests are usually constructed in exposed soil, or under 
the cover of stones, pavement, or other objects, and in rotting wood. 
The ants also nest in houses, most commonly around or between the 
lower masonry walls of the foundation. Entomologists are frequently 
asked to identify refuse from the nests of caespitum,; it is usually 
composed of small particles of gravel, seeds, fragments of dead insects, 
and sometimes fine wood fibers. Colonies are moderately large to 
large. Winged males and females have been seen every month of the 
year, most commonly during June and July. Smith, L. B., states that 
in the Norfolk, Va., area nuptial flights occur between June 20 and 
July 30. According to Donisthorpe, females are capable of founding 
colonies unaided by workers. The ants are almost omnivorous and 
feed on both dead and live insects, honey dew, seeds, the sap of plants, 
and various household foods such as meats, grease, nuts, potato chips, 
cheese, honey, and bread, but the ants seem to show a preference for 
meats or grease. Workers steal seeds from seed beds and girdle, scar, 
or scarify the roots or stems of tomatoes, cabbages, peppers, eggplants, 
carrots, beets, radishes, turnips, lettuce, parsley, Gaillardia, Coreopsis, 
and Aster. Lange has shown that workers of the pavement ant can 
often cause severe and extensive damage to sugarbeet plants by their 
attack on the germinating seed, and especially on the primary roots 
just below the crown. Plants were commonly killed by girdling while 
the ants were apparently seeking the sap. Workers are also known to 
gnaw into Irish potato tubers. They tend or foster plant lice and 
mealybugs, especially subterranean forms. An entomologist once 
found winged forms of this ant entangling and breaking threads in an 
acetate rayon-nylon manufacturing plant and soiling the threads. 
Unverified reports have been made of the ants gnawing holes in a 
child's rayon underwear and stinging or biting children, causing them 
to have an allergic rash or a skin reaction. 



HOUSE-INFESTING ANTS OF THE EASTERN UNITED STATES 47 

Workers of caespitum have been shown definitely to be -an interme- 
diate host of the poultry tapeworms Raillietina tetragona (Molin) and 
R. echinobothrida (Megnin). On a few occasions in the United 
States, queenless colonies of these ants (with workers) have been 
found to contain peculiar black (winged) females and pale, callow, 
wingless, pupoid males of a parasitic ant, Anergates atratulus 
(Schenck). This parasite is associated only with caespitum and is 
dependent on its host for food and care, since atratulus has lost its 
worker caste through parasitism. It has undoubtedly been introduced 
from Europe with its host species. 

References: Maria tt, 1898, pp. 3-i, fig.; Herrick, 1914, pp. 174, 176; Smith, 
1915, pp. 353-365 ; Bssig, 1926, pp. 862-863 ; Donisthorpe, 1927, pp. 193-198, fig. ; 
Wheeler, 1927, pp. 163-165 ; Walker and Anderson, 1937, pp. 312-314 ; Horsfall, 
1938, pp. 409-421; Rau, 1945, p. 119; O'Eourke, 1956, p. Ill; Lange, 1961, pp. 
1063-1064, fig. 

Tetramorium guineense (Fabricius) 

No universally approved common name has been given this species 
but on various occasions it has been called the Guinea ant. This intro- 
duced species is probably of African origin. It has been widely dis- 
seminated by commerce to various regions of the earth, especially the 
warmer ones. T. guineense is frequently intercepted in plant quaran- 
tine. In our more northern latitudes this ant frequently nests in 
freenhouses. It is most commonly encountered in the southern United 
tates, especially in the Gulf Coast region, where it occurs in both 
urban and rural areas, more commonly the former. 

Taxonomic Characters 

Subfamily and generic characters : Same as for caespitum,. Specific 
characters : Workers approximately 3-3.5 mm. long. Eye well devel- 
oped, strongly convex. Frontal carinae far apart, the distance between 
them gradually widening posteriorly, each forming a long scrobe for 
reception of antennal scape. Clypeus with three prominent longitu- 
dinal carinae. Prothorax (viewed from above) with very distinct 




Figure 25. Tetramorium guineense (Fabricius), lateral view of worker. 
748-356 O 65 4 



,48 TECHNICAL BULLETIN 1326, U.S. DEPT. OF AGRICULTURE 

angular shoulders. Thorax compressed on each side (best seen from 
above). Petiolar node, in profile, subrectangular. Body sculpture 
largely rugulose-reticulate, especially on thorax, petiole, and post- 
petiole ; gaster smooth: Body hairs fairly abundant, slender, suberect 
to erect, rather long. Body color varying from light brown to red- 
dish brown with a usually much darker gaster. 

Biology and Economic Importance 

Very little information has been published on the biology of this 
species. It is known, however, that guineense nests in small- to moder- 
ate-size colonies in exposed soil or under cover of stones and other 
objects, in rotting logs and stumps, in the stems of plants, and in the 
branches or under the bark of trees. The ants also nest in houses and 
buildings, and were once found in the drawer of an unoccupied desk. 
The species does not appear to be a house pest of major importance, 
if we are to judge from the small number of letters received from 
housekeepers concerning it. Workers are very fond of honeydew, and 
will tend plant lice and mealybugs. The ants also feed on dead and 
live insects. As house pests, they are almost omnivorous and feed on 
fruits, vegetables, meats, and grease. 

References: Phillips, 1934, pp. 23-24; Smith, 1936, pp. 851-852; Swezey, 1942, 
p. 179. 

Wasmannia auropunctata (Roger) 

. Little fire ant. The ESA-approved common name, "little fire ant," 
is misleading in that "fire ants" belong to the genus Solenopsis West- 
woodj and this species is not a Solenopsis or even closely related to it. 
It is true, however, that awopunctata, like species of /Solenopsis, has a 
"firelike" sting. This ant^ which is of Neotropical origin, has been 
introduced into several localities in Florida. It occurs in Mexico, 
Central and South America, and the West Indies. 

Taxonomic Characters 

Subfamily and generic characters: Workers are monomorphic. 
Frontal carinae far apart but partly concealing antennal insertions. 
Antenna 11-segmented. Abdominal pedicel composed of two seg- 




Figure 26. Wosmcmn/o auropunctata (Roger), little fire ant, lateral view of worker. 



HOUSE-INFESTING ANTS OF THE EASTERN UNITED STATES 49 

ments, the petiole and postpetiole. Sting present but not always 
exserted. Specific characters: Workers approximately 1.5 mm. long. 
Frontal carinae widely spaced, each forming a partial scrobe for re- 
ception of antennal scape. Antenna with a 3-segmented club; the 
last two segments of the club greatly enlarged and giving the false 
impression of a 2-segmented club. Apex of scape not attaining pos- 
terior border of head. Posterior border of head emarginate. Eye 
elongate, coarsely facetted, placed obliquely to longitudinal axis of 
head and forming a sharp angle, the apex of which is directed antero- 
ventrally. Dorsal surface of head punctulate, the posterior region 
with weak, longitudinal rugulae. Sculpture of thorax highly variable, 
rugulose, or rugulose-reticulate, or both. Prothorax (viewed from 
above) with angular humeri. Promesonotal suture absent or obso- 
lescent. Epinotal spines rather close together basally, each rather long 
and with acute apex. Petiolar node, in profile, subrectangular ; from 
above, very distinctly longer than broad. Hairs of body sparse, long 
and slender, widely distributed. Body color ranging from light brown 
to golden brown, gaster often slightly darkened. 

Biology and Economic Importance 

These ants nest in exposed soil and also in the soil beneath objects, 
in rotting wood, plant cavities, debris, under the bark or at the bases 
of leaf sheaths of plants and trees, and in houses. Nests in the soil are 
usually indefinite in form and may be compound ; it is often difficult 
to delimit the area of a nest. Nesting habits vary greatly with respect 
to ecological habitats and climatic conditions. The ants appear 
adapted to nesting in very dry to very moist areas. During drouth 
periods the ants nest deeper in the soil, and during floods the nests may 
even be moved into trees. Colonies are usually populous and may con- 
tain more than one reproductive queen. Because the ants are sensitive 
to cold, it is believed they are not capable of living outdoors in the 
colder regions of the United States. Workers are noted for their love 
of honeydew, which they obtain by tending plant lice, mealybugs, 
scales, and white flies ; workers have even been seen transporting im- 
mature stages of the cottony cushion scale, Icerya purchasi Maskell. 
Workers feed on dead insects, other arthropods, and small animals, 
and are probably predacious on many insects. The ants are especially 
noted for their painful and long-lasting stings, the effects of which 
may continue for several days. Allergic individuals may become pale 
and nervous or even shaky from several stings of these ants. Unlike 
Solenopsis spp., which sting on little or no provocation, the workers 
of auropunctata are not aggressive and sting only when pressed by 
clothing or other objects. However, so feared are they that it is diffi- 
cult to get laborers to work in groves or fields where these ants are 
abundant. In houses, they may infest clothing, beds, or food. Work- 
ers feed on bacon, fatty beef, peanut butter, olive and cottonseed oils, 
milk, juice of ripe oranges, or the oil of ripe avocados. They seem to 
show a preference for fat meats and oil. Since no complete biological 
study of this species has 'been made, the ants may have other habits 
inimical to man of which we are not aware. 

References: Wheeler, 1908a, pp. 143-144; Wheeler, 1919b, p. 304; Wolcott, 
1936, pp. 549-550 ; Smith, 1936, p. 854 ; Spencer, 1941, pp. 4-14 ; Fernald, 1947, 
p. 428; Wolcott, 1948, pp. 826-828; Osburn, 1948, pp. 11-12; Smith, 1950, p. 275. 



50 TECHNICAL BULLETIN 1326, U.S. DEPT. OF AGRICULTURE 

Attatexana (Buckley) 

Texas leaf -cutting ant, also known by such common local names 
as night ant, cut ant, parasol ant, pack ant, fungus ant, and red town 
ant. This native species occurs in eastern Texas and western Louisi- 
ana, largely between 92 and 101 long., but it is not necessarily uni- 
formly distributed over this area. Thirteen Louisiana parishes are 
infested. The species also occurs in northeastern Mexico. 

Taxonomic Characters 

Subfamily and generic characters : Polymorphic. Antenna 11-seg- 
mented, without a well-defined club. Head subcordate, strongly bi- 
lobed. Frontal carinae far apart, partly concealing antennal inser- 
tions. Dorsum of thorax with three pairs of prominent spines, the 
anterior ones the largest. Abdominal pedicel composed of 2 segments, 




Figure 27. -Afta texana (Buckley), Texas leaf-cutting ant, lateral view of worker. 

the petiole and postpetiole. Sting present but not always visible. 
Legs extraordinarly long. Specific characters: Workers 1-5-12 mm. 
long. Anterior border of clypeus with a median emargination, on 
each side of which there is a tooth. Mandible large, flattened, with a 
long masticatory border bearing numerous teeth. A spine present at 
posterior end of each frontal lobe. A longitudinal carina lying be- 
tween eye and frontal carina and terminating ventrally in a small spine. 
Each occipital lobe bearing two spines, a large one at posterior corner 
of head and a smaller one anterior to it. A small spine present on 
inferior angle of prothorax. Gaster without tubercles. Body densely 
and minutely punctate. Body usually dull dark brown or rust brown. 

Biology and Economic Importance 

Nests, found exclusively in the soil, are usually constructed in well- 
drained sand or loamy soils and commonly on slopes with a southern 
or western exposure. The central portion of the exterior part of the 
nest is usually higher than the remainder, and is composed of a differ- 
ently colored soil. The interior of the nest, which sometimes reaches 
a depth of 15 to 20 feet, contains innumerable chambers interconnected 



HOUSE -INFESTING ANTS OF THE EASTERN UNITED STATES 51 

by galleries with each other and with the surface of the soil. Walter 
et al., counted 911 chambers in a single large nest. Within many of 
the chambers the ants grow a specific fungus on a substratum composed 
largely, if not entirely, of macerated leaves. The adult ants not only 
feed on the fungus but they also feed it to their brood, which develop 
within the chambers. The minor workers cultivate the fungus and 
care for the brood, the medium-size workers cut and transport the 
leaves to the nest, and the very large workers guard the nest. The sur- 
face of the soil above the nest bears numerous holes, each surrounded 
by crescent- or crater-shaped piles of earth. These piles vary greatly 
in size and are usually most numerous above the central exterior part 
of the nest, becoming more widely and irregularly spaced laterally. 
The galleries leading from the craters to the interior of the nest 
ventilate and regulate the interior temperature and moisture, and allow 
for the passage of leaves brought in by the workers and for the exit of 
ants at the time of the nuptial flight. A very large nest may occupy 
an exterior surface of 4,500 square feet and have 1,000 or more entrance 
holes. Some nests are very old, the colony having occupied the same 
general nesting site for more than 60 or 70 years. 

Workers frequently forage from 300 to 600 feet from the nest and 
make conspicuous foraging paths. During the summer they forage 
mostly at night, but in the fall, winter, or spring when the air tempera- 
ture ranges oetween 45 and 90 F., foraging takes place during the 
day unless it is too cold or wet. The ants cut leaves from almost any 
type of plant, but Wheeler stated that they attack only one type of 
plant at a time ; he thought they preferred small or narrow leaves re- 
gardless of texture. Also transported by the ants are the floral parts 
of plants, caterpillar droppings, Spanish moss, seeds of juniper, hack- 
berry, and yaupon, corn, cornmeal, flour, rice, peas, wheat, oats, chops, 
bread, cake, chickenfeed, sugar, beans, ground coffee, and even chew- 
ing tobacco. 

The nuptial flights take place from early April into June. Walter 
et al stated that the flights occur on clear, moonless nights and that 
immense numbers take part in the flights. J. C. Moser (unpublished 
data) also found that the nuptial flights took place just before dawn 
on dark, still, moonless nights. He also noted that a single colony 
was capable of giving off successive flights over a period of weeks be- 
fore exhausting itself of sexual forms. At one time it was thought that 
a single colony contained only one reproductive female or queen, but 
Moser has recently found as many as five wingless, presumably fertile 
females in a single colony. No one has made a detailed count of the 
number of individuals in a colony, but in a very large one it must run 
into as many as several hundred thousands. 

The ants may affect man by invading his house and stealing fari- 
naceous or other foods, by cutting leaves from his domesticated plants, 
by stealing seeds, by building unsightly nests on his premises, and by 
damaging roads, walks, stock, or equipment by cave-ins of the nests. 
When a nest is broken into and the ants are greatly disturbed, the large 
workers can inflict painful bites which often produce blood. McCook 
stated that the bites of workers are not as painful as are the stings of the 
harvesting ant Pogonomyrmex barbatus (F. Smith) . Frequently, the 



52 TECHNICAL BULLETIN 1326, U.S. DEPT. OF AGRICULTURE 

workers attach themselves so firmly to clothing, and hold on for such 
long periods that the clothes can go to the laundry and be returned 
with the heads of the ants still attached. 

References: McCook, 1879, pp. 33-40; Wheeler, 1907, pp. 729-742; Hunter, 1912, 
pp. 1-4 ; Snyder, 1937, pp. 14-17 ; Walter, Seaton, and Mathewson, 1938, pp. 1-18 ; 
Smith, 1939, pp. 1-11. 

Iridomyrmex humilis (Mayr) 

Argentine ant. This species, which is native to Brazil and Argen- 
tina, has been widely distributed by commerce to numerous parts 
of the world. It was apparently brought into New Orleans on coffee 
ships from Brazil sometime before 1891 and spread rapidly over most 
of the Southern States. Largely confined to urban areas, hwnilis 
is now established in many localities in the Southern States, except 
Kentucky and Virginia. It also is widely distributed in California. 
Small localized infestations occur hi St. Louis, Baltimore, and Chicago. 

Taxonomic Characters 

Sub j 'amity and, generic characters: Monomorphic. Antenna 12- 
segmented, without a club. Antennal fossa touching posterior border 
of clypeus. Eye placed well toward the median line of the head. 
Maxillary palpus neither long nor with unusually long third segment. 
Promesonotal suture distinct. Mesoepinotal region with a strong con- 
striction or impression. Abdominal pedicel composed of a single 
segment, the petiole. Petiolar scale well developed, inclined or sub- 
erect, usually easily seen in profile. Cloacal orifice ventral, trans- 
verse, slit-shaped, and without a fringe of hairs (fig. 31,co). Integu- 
ment soft and flexible. Specific characters: Workers 2.2-2.6 mm. long. 
Body slender. Head oval or somewhat subtriangular. Clypeus dis- 
tinctly broader than long, convex in middle, and with broad emargi- 
nation on its anterior border. Eye well-developed, with approxi- 
mately 12 to 14 ommatidia in its greatest diameter. Apex of scape 
noticeably surpassing posterior border of head. Mandible with two 
large apical teeth, followed by a number of small, irregular teeth or 
denticulae. In profile, promesonotum forms a long gentle unbroken 
arch in front of mesoepinotal impression or constriction. Epinotum 




Figure 28. Iridomyrmex humilis (Mayr), Argentine ant, lateral view of worker. 



HOUSE-INFESTING ANTS OF THE EASTERN UNITED STATES 53 

in profile very distinctly higher than long, with convex base and flat- 
tened declivity. Body hairs sparse, normally absent from thorax. 
Body color more or less uniform light brown or brown. Workers, 
when freshly crushed, emit a stale, greasy or musty odor. 

Biology and Economic Importance 

Although much of the wide distribution of the Argentine ant in the 
United States has resulted from commercial shipments of plants and 
plant products, building materials, household goods, groceries, and 
other materials, the species has also been disseminated to a lesser de- 
gree by natural means, including heavy rains and floods. This ant's 
success as a competitive species can be attributed to its ability to nest 
in diverse types of habitats, to produce prodigious numbers of in- 
dividuals because of the many reproductive females in a colony, to 
thrive on a wide variety of foods, to live on a friendly intercolony 
basis with its own species, and to exterminate other species of ants. 
It is an arch enemy of the Southern fire ant, Solenopsis xyloni McCook, 
a species with which it has to compete for both space and food. It nests 
in exposed soil and soil under cover, and also occurs in rotten wood, 
faulty places in trees, refuse piles, bird nests, bee hives, and other 
places. 

Males and winged females are normally produced in the spring, 
usually in April or May. Since nuptial flights are seldom if ever 
witnessed, it is assumed that most mating takes place in the nest. In 
regard to the nuptial flights, Skaife writes as follows concerning this 
ant at the Cape in South Africa : "There is no nuptial flight at all in 
the case of the Argentine ant. I have never seen even the semblance 
of a nuptial flight during the many years I have kept this species 
under observation. What happens at the Cape is this: On hot, still 
nights after midsummer, particularly if rain is threatening, winged 
males leave the nests. They often come to lights at this time, but no 
females are to be seen among them. I have never come across a winged 
female outside the nest. The young queens stay at home, and there 
they are sought out by the males, from other nests as well as their own, 
and there the mating takes place." New colonies apparently are 
formed by one or more fertile females, migrating from the mother 
colony accompanied by a group of workers. The female seems unable 
to raise her brood alone. In winter especially, several colonies may 
combine to form larger colonies in favorable nesting sites. In early 
spring or summer the large winter colonies may divide into a number 
of smaller colonies or units. Workers are predaceous, carnivorous, and 
granivorous. They feed on the secretions of the floral and extrafloral 
parts of certain plants, gnaw into the buds of some fruit trees such as 
citrus, or even into ripened fruits such as figs. Workers tend and fos- 
ter injurious honeydew-excreting insects such as plant lice, scales, and 
mealybugs ; the resulting damage is severe in citrus groves and sugar- 
cane plantations. The number of individuals present in an area where 
this ant is well established is beyond comprehension. The very active 
workers get into every conceivable place both in and out of doors. They 
exterminate all native ants except a few small, nonaggressive species. 
The Argentine ant becomes the one dominant form in an area infested 
by it. Large files of workers can be seen running up and down trees, 



54 TECHNICAL BULLETIN 1326, U.S. DEPT. OF AGRICULTURE 

on fences, the ground, and elsewhere. Although common in urban areas 
and regarded as a city-loving ant, the species has also become well es- 
tablished in rural areas. 

The Argentine ant is one of the most persistent and troublesome of 
all our house-infesting ants. Native ants normally infest houses at 
random, frequently only in small numbers and for only short periods 
of time. Argentine ants, on the other hand, will infest every house 
persistently, continuously, and in large numbers, once they are well 
established in a given area. Extremely cold weather will cause the 
ants to enter a period of inactivity or dormancy, but a thaw or an un- 
usually warm period will result in the ants resuming activity. A 
housekeeper in an infested area can expect to have trouble in her home 
year after year unless the ants are fought on a community basis. 
Workers feed on almost every type of food, including sweets, meats, 
pastries, fruits, dairy products, eggs, animal fats, and vegetable oils. 
The ants are especially fond of sweets. Although the amount of food 
eaten may not be large, the housekeeper usually throws the remainder 
away because of contamination. In addition, the ants make them- 
selves objectionable by crawling on or in every imaginable place such 
as stoves, refrigerators, shelves, beds, and clothing. The worker ant 
has no sting. Its bite is rather feeble, and usually occurs only on prov- 
ocation. The ants also steal seeds from seedbeds, disrupt or destroy 
bee colonies, drive setting hens from the nest, especially when the eggs 
are accidentally broken, and kill hatching chicks. Their habit of 
crawling everywhere, especially over refuse, filth, sputum, faeces, car- 
rion, or sewage, affords them an opportunity to transport the causative 
organisms of dysentery, typhoid fever, and tuberculosis. 

References: Newell, 1908, pp. 20-34; Newell, 1909, pp. 174-192; Newell and 
Barber, 1913, pp. 1-98, figs. ; Smith, 1936, pp. 1-39, fig. ; Metcalf and Flint, 1939, 
pp. 764, 769 ; Smith, 1950, pp. 285-287 ; Skaife, 1962, p. 12. 

Iridamyrmex pruinosus (Roger) 

This native species ranges from Wisconsin to New York, south to 
New Mexico and Florida, and also occurs in the West Indies. It is 
not only common, but widely distributed in the southern United States. 

Taxonomic Characters 

Subfamily and generic characters: Same as for hwmilis. Spe- 
cific characters: Workers 1.8-2.5 mm. long. Head subrectangular. 
Clypeus broader than long, moderately convex, its anterior border 
rounded, nonemarginate. Mandible with five to six teeth on mastica- 
tory border, these decreasing in size (but not uniformly) from apex to 
base. Apex of scape distinctly surpassing posterior border of head. 
Erect hairs rather sparse on body ; dorsal surface of thorax with a few 
erect hairs on pronotum and epinotum, and occasionally on mesonotum 
(frequently hairs are lacking on one of these regions, especially on 
mesonotum or epinotum) . Body covered with dense grayish or pru- 
inose pubescence which in some lights conceals the ground surface and 
in other lights fails to do so. Body color highly variable, commonly 
uniform dark brown or black, or with gaster lighter. Easily dis- 



HOUSE-INFESTING ANTS OF THE EASTERN UNITED STATES 55 




Figure 29. Iridomyrmex pruinosus (Roger), lateral view of worker. 

tinguished from humilis by shape of head, difference in mandibular 
dentition, presence of erect hairs on thorax, stouter and more densely 
pubescent body, and by the odor of fresh specimens, which is like rotten 
coconut in pruinosus and a stale musty or greasy odor in humilis. 

Biology and Economic Importance 

The ants seem to prefer open habitats such as fields, meadows, pas- 
tures, and entirely bare areas, and will also nest in open woods out of 
dense and prolonged shade. Nests are constructed in exposed soil or 
soil under the cover of stones, other objects, and under the bark of 
logs and stumps. Entrance holes of nests in the soil commonly have 
crater-shaped mounds of earth surrounding them, but the craters 
may be imperfectly shaped, or the ground may be more or less bare. 
Colonies are small to moderate-sized. Males and winged females have 
been observed in Florida from May into July. Workers are very fond 
of honeydew, and tend honeydew-excreting insects; they also live 
on both live and dead insects. The very agile, fast-moving workers 
form pronounced foraging trails. M. 'S. Blum, in a letter to the 
author, wrote that the ants lay down on their foraging trails a methyl- 
n-amyl ketone substance, which is emitted from the gaster. Workers 
have been induced to follow artificial trails on which this synthetic 
chemical has been placed. The odor emitted by live or freshly killed 
workers has been likened to that of rotton coconuts and is similar to the 
odor of ants of the genus Tapinoma. 

This species is a house pest particularly in the Gulf Coast States. 
Most frequently the ants invade houses from outdoors, but it is quite 
likely that they may nest within houses as well. Although workers 
feed on most of the foods commonly eaten by ants, they seem to show 
a preference for sweets. This ant may be an intermediate host of the 
poultry tapeworm Raillietina tetragona (Molin), since worker ants 
have been seen carrying gravid segments of the tapeworm into their 
nests. 

References: Wheeler, 1905b, p. 389; Dennis, 1938, pp. 271-272, 294; Cole, 1940, 
pp. 64-65 ; Case and Ackert, 1940, pp. 393-395 ; Hess, 1958, pp. 43-45, 55-60, 62-64 ; 
Van Pelt, 1958, p. 39. 



56 TECHNICAL BULLETIN 1326, TJ.S. DEPT. OF AGRICULTURE 

Dorymyrmex pyramicus (Roger) 

Pyramid ant. It is also known as the lion ant because of its aggres- 
sive habits. D. pyramicus is a native species, which ranges from 
Oregon to New York and south to California and Florida. Although 
this species is widely distributed over most of the United States, it is 
probably more common in the southern half. It has also been recorded 
from Mexico, South America, and the West Indies. 

Taxonomic Characters 

Subfamily and generic characters : Workers monomorphic. Anten- 
nal fossa touching posterior border of clypeus. Antenna 12-segmented, 
without club. Eye placed well toward median line of head. Man- 
dible with five to six teeth, the apical tooth very long and pointed. 
Maxillary palpus unusually long, 6-segmented; third segment ap- 
proximately as long as combined lengths of fourth, fifth, and sixth. 
Ventral surface of head with a weakly developed psammophore. 
Thorax with distinct promesonotal and mesoepinotal sutures. Pos- 
terodorsal surface of epinotum conical or tuberculiform. Legs long 
and slender. Abdominal pedicel composed of a single segment, the 
petiole. Petiole well developed, scalelike, suberect to erect, narrow 
or thin in profile. Base of gaster with an impression. Cloacal orifice 
ventral, transverse, slitshaped, without a fringe of hairs (fig. 31, co) . 
Sting lacking. Anal glands present, producing a characteristic dis- 
agreeable, rotten-coconut odor. Integument soft, flexible. Specific 
characters : Workers approximately 3 mm. long. Mesonotum in pro- 
file forming a perceptible angle anterior to the mesoepinotal suture. 
Body hairs sparse, thorax usually without erect hairs. Pubescence 
fairly dense on thorax and gaster, causing these regions in some lights 
to appear subopaque and in other lights to be noticeably shiny. Body 
color highly variable, ranging from almost uniform light brown to 
uniform dark brown or blackish, with gaster frequently darker than 
head and thorax. 




Figure 30. Dorymyrmex pyramicus (Roger), pyramid ant, lateral view of worker. 



HOUSE-INFESTING ANTS OF THE EASTERN UNITED STATES 57 

Biology and Economic Importance 

Nests are constructed in the soil, usually in open sunny places such 
as meadows, pastures, sandy or bare areas; seldom under objects. 
The typical nest has a single opening leading by a gallery to a chamber 
which is usually near the surface of the soil. The excavated earth 
is thrown up around the central nest opening in a circular crater, usu- 
ally about 2 to 4 inches or larger in diameter. Sometimes it is a semi- 
circular or irregular mass, or it is not present at all. The ants nest in 
various types of soils such as sand, loam, clay, or limestone chalk. 
Nests are frequently built in, or very near, the nests of other ants, 
such as the harvesting ants Pogonomyrmex occidentalis and P. Ixtirba- 
tus. Colonies are small to moderate-sized, containing up to only a few 
thousand individuals. In Mississippi, male and female pupae have 
been observed in nests in late May. Observations indicate that in some 
nests, males and females can pass the winter in the adult stage. 
Workers are agile and fast-moving, and forage in conspicuous files. 
They are highly carnivorous and predacious, but they are exceedingly 
fond of honeydew, and tend insects excreting this substance. I have 
witnessed them attacking larvae of the corn earworm Heliothis sea 
(Boddie). Another observer has seen them attacking workers of 
the fire ant Solenopsis geminata. D. 'pyramiciis is economically im- 
portant because of its house-infesting habits, and the numerous and 
ugly mounds it builds on lawns. Workers commonly invade houses 
from outdoors. They feed on a wide variety of human foods but 
seem to show a preference for sweets. I have received unverified 
reports of these ants biting children. 

References: Smith, 1936, pp. 864-865; Cole, 1940, pp. 30, 61-62; Mallis, 1941, 
p. 76 ; Hess, 1958, pp. 40-42, 55-59, 62-64. 

Tapinoma sessile (Say) 

Odorous house ant. A native species, which ranges from Canada 
through the entire United States and into Mexico. In some of our 
States, the ants may be absent from desert areas. 

Taxonomic Characters 

Subfamily and generic characters: Monomorphic. Antenna 12- 
segmented, without club. Antennal fossa touching posterior border 
of clypeus. Eye located well toward median line of head. Middle of 
anterior border of clypeus emarginate. Mandible with two apical 
teeth followed by a number of smaller teeth or denticulae. Prome- 
sonotal and mesoepinotal sutures distinct, the latter very pronounced. 
Flattened and sloping declivity of epinotum very distinctly longer 
than base of epinotum. Abdominal pedicel a single segment, the 
petiole. Petiolar node vestigial, strongly flattened or inclined, con- 
cealed from above by base of gaster. Cloacal orifice ventral, trans- 
verse, slit-shaped, not surrounded by a fringe of hairs (fig. 31,co). 
Sting lacking. Anal glands present, which produce a characteristic 
disagreeable, rotten-coconutlike odor. Suberect or erect hairs very 
sparse on body, absent from thorax. Integument soft, flexible. Spe- 
cific characters: Workers 2.4-3.25 mm. long. A prominent suberect 



,58 TECHNICAL BULLETIN 1326, U.S. DEPT. OF AGRICULTURE 




Figure 31. Tapinoma sessile (Say), odorous house ant: a, Lateral view of worker; fc, ventral 
surface of apex of gaster; co, the transverse, slit-shaped cloacal orifice. 

or erect hair on each side of clypeal emargination best seen in profile. 
Body color variable, ranging from more or less uniform brown to 
uniform black. 

Biology and Economic Importance 

This common and widely distributed ant is one of our most adapta- 
ble species, occurring from sea level to 10,500 feet. It nests in a wide 
variety of habitats, ranging from sandy beaches, pastures, open fields, 
woodlands, and bogs, to houses. Most nests in the soil are beneath 
objects such as stones or logs, but this versatile species also nests under 
the bark of logs and stumps, in plant cavities, insect galls, refuse, piles, 
and bird and mammal nests. Nests in the soil are indefinite in form, 
shallow, and of little permanency. The colonies range in size from a 
few hundred individuals to many thousands, and contain numerous 
reproductive females. The individuals of the various colonies are 
not antagonistic to each other, but are hostile to the introduced Argen- 
tine ant. Mating takes place in the nest between males and their sister 
females, but nuptial flights have also been observed. Although females 
have been observed to establish colonies independently, it is also highly 
possible that the ants may form new colonies when one or more fertile 
females leave the parental colony accompanied by a number of work- 
ers. Workers are active and rapid, and normally travel in files. 
When alarmed, the workers dash around excitedly in an erratic man- 
ner, quite often with the posterior part of their abdomen elevated. 
Workers also emit from their' abdominal glands an odor which has 
been likened to that of rotten coconut. In Mississippi, male pupae 
have been noted from April 16 to 30, and males and winged females 
from May 1 to 15. In Dogs in southeastern Michigan, Kannowski 
has observed nuptial flights from June 26 to July 15. Few ants exceed 
sessile in their love for honeydew. Not only do workers eat honeydew 
avidly, but they assiduously attend such honeydew-excreting insects 
as plant lice, scale insects, mealybugs, and membracids. In some in- 
stances, workers have been observed transporting live plant lice. 
When mealybugs have been disturbed by collectors, the worker ants 
have tried to pick them up and carry them away. Workers visit the 
floral and extrafloral nectaries of plants in search of their glandular 



HOUSE-INFESTING ANTS OF THE EASTERN UNITED STATES 



59 



secretions. Like many species of ants, the workers feed on both dead 
and live insects. 

T. sessile, one of our more important house infesting ants, is capable 
of invading houses from outdoors, or nesting inside. Although the 
ants feed on a wide variety of household foods, such as raw and cooked 
meats, cooked vegetables, dairy products, fruit juices, and pastries, 
they appear to show a preference for sweets. Their active habit of 
crawling over plants in search of honeydew may eventually incrimi- 
nate them in the transmission of plant diseases. 

References: Esslg, 1926, pp. 863-864, flg.; Smith, 1928, pp. 307-329, figs.; 
Metcalf and Flint, 1939, p. 770 ; Cole, 1940, pp. 14, 30, 63-64 ; Smith, 1950, pp. 
283-284 ; Kannowski, 1959, pp. 126-129. 

Tapinoma melanocephalum (Fabricius) 

Although probably of African or Oriental origin, this introduced 
species has been so widely distributed by commerce that it is impossi- 
ble to determine its original home. The species is established in a 
number of localities in southern Florida. In more northern latitudes, 
melanocephalum seems unable to maintain itself, except in green- 
houses or perhaps heated buildings. 

Taxonomic Characters 

Subfamily and generic characters: Same as for sessile. Specif/} 
characters: Workers extremely small, 1.3-1:5 mm. long. Apex of 
scape distinctly exceeding posterior border of head. Antennae and 
legs somewhat thickened in appearance. Prothorax compressed later- 
ally and with rather pronounced shoulders. Thorax broadest through 
anterior part of prothorax. Appendages very pale or milky white 
in color. Head usually darker than remainder of body, thorax and 
gaster commonly with light and dark areas of variable size. Dorsum 
of thorax without erect hairs. This species is readily recognized by 
its extremely small size and peculiar color markings. T. melano- 
cephalum and Solenopsis molesta are the smallest ants discussed in 
this paper. 




Figure 32. Tapinoma melanocephalum (Fabricius), lateral view of worker. 



60 TECHNICAL BULLETIN 1326, U.S. DEPT. OF AGRICULTURE 

Biology and Economic Importance 

This unusually small ant is highly adaptable in its nesting habits. 
It is found in the soil, rotten wood, decayed parts of trees or under 
the bark, in plant cavities, houses, and greenhouses. Colonies may be 
moderate to large in size ; they contain numerous reproductive females. 
The members of different colonies are not antagonistic to each other. 
New colonies probably are formed by the migration of one or more 
reproductive females accompanied by a number of workers. It is not 
definitely known whether the ants may also establish new colonies by 
means of nuptial flights. Workers have a habit of running rapidly 
and erratically. They can emit an odor like that of rotten coconuts 
("Tapinoma-like") . Workers are very fond of honey dew and tend 
honeydew-excreting insects for this substance. They also feed on both 
dead and live insects. 

Pimentel has shown that in Puerto Rico, worker ants destroy eggs 
and first-stage larvae of the housefly Musca domestica (Linnaeus). 
There, the ants are known locally as albaricoque, and in Cuba as hor- 
miga bottegaria. In Cuba, the ants are known to disseminate the grass 
root mealyoug Ripersia radicicola Morrison, on the roots of sugarcane. 
The species is important as a house pest. Not only can the ants invade 
houses from outside, but can nest within the house as well. Although 
the ants feed upon many household foods, they seem to show a prefer- 
ence for sweets, having been observed feeding on sugar, cakes, and 
fountain syrup. 

References: Wheeler, 1919a, pp. 275-276 ; Wheeler, 1926, pp. 154, 156; Stahl and 
Scaramuzza, 1929, pp. 6-7 ; Phillips, 1934, pp. 20-21 ; Smith, 1936, pp. 861-862 ; 
Eidmann, 1944, p. 459 ; King, 1948, p. 395 ; Pimentel, 1955, p. 29. 

Camponotus castaneus (Latreille) 

This native species ranges from Iowa to New York, south to Texas 
and Florida. It is perhaps most abundant in the southeastern United 
States. Although rather widely distributed, it is relatively uncommon 
in many areas. 

Taxonomic Characters 

Suib family and generic characters: Polymorphic. Antennal fossa 
not touching posterior border of clypeus. Antenna articulated at a 
considerable distance from posterior border of clypeus. Antenna 12- 
segmented, without a club ; funiculus slender. Clypeus distinctly cari- 
nate. Eye well developed. Pronotum more or less flattened (best seen 
in profile). Abdominal pedicel composed of a single segment, the 
petiole. Cloacal orifice terminal, circular, surrounded by a fringe of 
hairs (fig. 48,co). Sting lacking. Workers capable of emitting a 
strong formic acid odor. Specific characters: Large ants, workers 
7-10 mm. long. Head (mandibles excluded) as long as wide, or longer 
than wide. Cheeks without erect hairs. Apex of scape noticeably sur- 
passing posterior border of head ; funiculus unusually slender. Cly- 
peus distinctly but not strongly carinate ; middle of anterior border of 
clypeus extended forward as a lobe, its anterior border scalloped. 
Epinotum with indistinct boundary between base and declivity. Mid- 
dle and hind tibiae each with a row of graduated bristles; no erect 



HOUSE-INFESTING ANTS OF THE EASTERN UNITED STATES 61 




Figure 33. Compono/us ccrsfaneus (Latrellle), lateral view of worker. 

hairs except at apex of each of these segments. Pubescence extremely 
sparse and closely appressed on body, almost lacking. Body dis- 
tinctly shiny. Color ranging from yellowish to yellowish red, head 
and gaster commonly darker than thorax. 

Biology and Economic Importance 

C. castaneus constructs its nests in rotten logs and stumps, in ex- 
posed soil, or in the soil under the cover of objects; also in combined 
log and soil media. Van Pelt states that he found colonies rare in the 
Blue Kidge Mountains at altitudes between 4,600 and 5,000 feet. Col- 
onies are small to moderate in size, consisting of a few hundred to sel- 
dom more than a thousand or so individuals. Data on the formation 
of colonies are very limited. It appears, however, that a new colony 
is founded independently by a newly fertilized female, and that there 
may not be more than one reproductive female per colony. Our rec- 
ords indicate that in the greater Washington, D.C., metropolitan area, 
males and winged females may be produced during April or May, 
since these sexed forms have been taken outside of, or away from, 
their nests from May to mid- June. Most, if not all, the nuptial flights 
apparently take place at night. In some colonies there is evidence 
that males and winged females overwinter in the parental nest, and 
do not make their nuptial flight until the following year. Workers 
appear very timid or excited when their nest is exposed, dashing mad- 
ly and rapidly about trying to hide. Like many ants, the workers 
tend honeydew-excreting insects for the palatable honeydew. Work- 
ers also feed on both live and dead insects. 

Although castaneus frequently infests houses, it is not a species of 
major importance. Workers are largely crepuscular or nocturnal, in- 
vading houses principally after dusk and commonly disappearing be- 
fore daybreak. Workers usually appear in small numbers in houses, 
and often show little interest in household foods. Apparently they 
are fond of sweets, since they have been reported feeding on sugar 
and angel cake. The author lived in his home for 16 years before 
castaneus workers invaded his kitchen; they remained only a short 



62 TECHNICAL BULLETIN 1326, U.S. DEPT. OF AGRICULTURE 

while and disappeared without his having to resort to control meas- 
ures. The ants have never appeared in the house again, although 
it has been 7 years since the invasion. Although workers commonly 
invade houses from outdoors, there have been instances when it ap- 
peared that they may have been nesting within the house. 

References: Wheeler, 1910a, p. 323; Smith, 1924, pp. 123-124; Wesson and Wes- 
son, 1940, pp. 90, 103 ; Cole, 1940, pp. 14, 30, 84 ; Van Pelt, 1958, pp. 41-13 ; Van 
Pelt, 1963, p. 212. 

Camponotus tortuganus Emery 

A native species, which ranges over at least the southern half of 
Florida, including the Keys and the Tortugas, it has been collected as 
far north as Orlando (Orange County). 

Taxonomic Characters 

Subfamily and generic characters : Same as for castaneus. /Specific 
characters : Large ants, workers 6-11 mm. long. Head very noticeably 
longer than broad and narrowed anteriorly. Anterior margin of 
clypeus extended forward as a prominent lobe, the anterior border of 
which is slightly excised or emarginate. Frontal carinae placed close 
to each other, elongate, lyrate. Eye prominent, strongly convex. Cly- 
peus with a sharp, well-defined carina. Base of epinotum very notice- 
ably longer than declivity. Tibiae of all legs without erect hairs. 
Each middle and hind tibia without a row of graduated bristles on the 
flexor surface, but with a sulcate lateral surface. Body hairs fairly 
abundant, long, yellowish or golden, according to the light. Head, 
thorax, and petiole finely shagreened, subopaque. Body color fer- 
ruginous brown, head darker than thorax ; gaster dark brown or black 
but subject to much variation in color, with light bands or spots on 
some of the segments. Head commonly with areas of infuscation. 

Biology and Economic Importance 

Except for a brief biological note by Wheeler, nothing has been pub- 
lished on the biology or economic importance of tortuganus, although 




Figure 34. Componofus torfaganm Emery, lateral view of worker. 



HOUSE-INFESTING ANTS OF THE EASTEBN UNITED STATES 63 

it is a frequent house pest. Almost all of the information presented 
here has been compiled from statements, unfortunately lacking in de- 
tail, from housekeepers in submitting specimens for determination. 
Random notes and observations indicate that tortuganus nests in small 
colonies in rotting wood and in the soil beneath stones. Although the 
ants may invade houses from outdoor nests, they also live in houses, 
where they may be a pest for long periods of time. The ants have been 
reported to nest in the sidings, rafters, and possibly the porch roof of 
houses, but there is no indication of the amount of damage the ants 
caused. Even house trailers are not immune to invasion. Workers can 
be especially active after dark, but this does not preclude diurnal activ- 
ity as well. No records are available of the food habits of tortuganus. 
Should the species follow the pattern of most Camponotus species, the 
workers may be expected to feed on honeydew and small insects. 
Large numbers of males and winged females have been collected in 
houses from late May to mid- July. 
Reference: Wheeler, 1932, pp. 13-14. 

Camponotus pennsylvanicus (DeGeer) 

Black carpenter ant. A native species, this ant ranges from North 
Dakota to Quebec and Ontario, and south to Texas and Florida. It is 
of especial interest historically because it was the first native North 
American species to be described (DeGeer, 1773) . 

Taxonomic Characters 

Subfamily and generic characters : Polymorphic. Abdominal pedi- 
cel composed of a single segment, the petiole. Cloacal orifice terminal, 
circular, surrounded oy a fringe of hairs (fig. 48,co). Sting lacking. 
Workers capable of emitting a strong formic acid odor. Head of 
largest workers as broad as long, broader behind than hi front, and 
of a very stout appearance. Antenna 12-segmented, without a club. 




Figure 35. Camponotus pennsy/rcrnicus (DeGeer), black carpenter ant, lateral view of 

worker. 
749-3EW O 65 5 



64 TECHNICAL BULLETIN 1326, U.S. DEPT. OF AGRICULTURE 

Scape flattened basally, noticeably thickened toward the apex, extend- 
ing past the posterior corner of the head except in the largest workers. 
Antennal fossa well separated from the posterior border of the clypeus. 
Frontal carinae lyrate in shape. Eye well-developed, flattened or 
weakly convex, nearer the posterior border of the head than to the base 
of the mandible. Clypeus ecarinate or else scarcely carinate in largest 
workers. Middle of the anterior border of the clypeus extended as a 
slight lobe. A deep impression or fossa on the lateral border of the 
clypeus, especially in the largest workers. Pronotum flattened ; notice- 
ably so in the larger workers. Specific characters : Large ants, work- 
ers 6-13 mm. long. Body color typically black but some individuals 
may have reddish thoracic pleuron, petiole, and legs. Thorax and 
gaster typically subopaque or opaque, the gaster covered with dense, 
long, appressed, pale yellowish or ashy pubescence. Body hairs sub- 
erect or erect, yellowish, and moderately abundant. Species subject 
to considerable variation in color and sculpture. Variation in color 
especially apparent on thorax and petiole, which may be very light red 
or brown. Sculpture of head and thorax may also be weaker, making 
them more shiny than in typical form. Typical form, however, readily 
distinguished by black body and long, appressed, pale yellowish or 
ashy-colored pubescence on dorsum of gaster. 

Biology and Economic Importance 

Exclusively (or almost so) a wood-nesting form, Gamponotus penn- 
sylvanicus is one of our best known and most adaptable ants. It is 
especially common in the eastern and central United States. Van 
Pelt has found colonies of this species common in the Blue Ridge 
Mountains at altitudes between 3,500 and 5,500 feet. The life history 
of the species, as studied by Pricer at Urbana, 111., is briefly as follows : 
Nuptial flights of overwintering males and females in parental colonies 
take place from May to late July. A single, fertilized female estab- 
lishes a nest in a self-made, or preformed, cavity, usually under 
the bark of a tree, log, or stump; this is done without the aid of 
workers. In this sealed cavity she brings her first brood of workers 
(usually up to 27 or more individuals) to maturity on her salivary 
secretions. During this time she does not gather any food for herself 
from outside the nest. Since the first brood does not have an ample 
supply of food, the workers are small (minor workers). The next 
and following broods are all fed by the workers, and as the food supply 
gradually increases, so does the size of the workers produced. After 
a number of years, a colony will contain numerous workers of various 
sizes, some of the largest being extraordinarily large (major workers) . 
Workers too large to be called minor, and too small to be called major, 
are designated as intermediate workers. The number and size of work- 
ers progressively increases each year at a much accelerated rate until 
the colony reaches maturity, at which time there will be present not 
only a few thousand workers, but males and winged females, and nu- 
merous eggs : larvae, and pupae. 

Pricer estimated that a colony could not produce males and winged 
females until it contained approximately 2,000 or more workers, and 
that to do this, a colony must be at least 3 to 6 or more years old. The 
largest colony he observed contained 3,018 workers, a reproductive fe- 



HOUSE-INFESTING ANTS OF THE EASTEKN UNITED STATES 65 

male, 196 winged or virgin females, 174 males, and 842 larvae. No 
doubt there are colonies that considerably exceed this number of in- 
dividuals. Pricer believed that after a colony has once started to 
produce males and winged females, it will continue to do so each year 
for an indefinite period. During winter, when reproduction ceases, the 
immature stages live in the colony as larvae. A mature colony, during 
the warm months of the year, may contain a reproductive female, 
winged females, males, workers, eggs, larvae, and pupae. It is normal 
for a colony to have a single queen. In life-history studies of this ant, 
McCook found that the first-brood workers were reared in late June 
or early July, and required 60 days to pass from the egg to the adult 
stage. 

Under natural conditions, black carpenter ants nest in live and dead 
standing trees and in rotting logs and stumps, but they are also 
adapted to nesting in houses and buildings, telephone and telegraph 
poles, or in other wood or wood products used by man. The ante nest 
in logs and stumps, which vary widely in degree of decay and moisture 
content. Most observers maintain that carpenter ants enter live trees 
through cracks, scars, knot holes, and decayed or faulty places. Once 
inside the tree, they remove the faulty wood and extend their burrows 
into the adjacent sound wood. It would appear that almost all types 
of trees may be attacked. The ants have been recorded from poplar, 
cherry, white and pitch pine, balsam, elm, willow, maple, hickory, 
chestnut, cottonwood, juniper, aspen, and scarlet, red, black, white, 
and post oaks. This list no douot is incomplete. Graham thought 
that this species and ferrugineus did considerable damage to standing 
white cedar trees in Minnesota, For remarks on this finding, see foot- 
note on femtgineus, p. 69. 

Although nests are frequently only a few feet from ground level, at 
times they can be very high in trees. McCook reported that the top 
of a white pine nearly 75 feet from the ground was nearly cut off by 
the excavation of these ants. Felt (McCook, 1876) stated that two 
balsam trees were so riddled by galleries of ants, the trees broke off 
during a heavy wind storm. The black carpenter ant is generally 
regarded as a wood-nesting species. Although it has been reported 
nesting in the soil, such reports should be questioned, for in most, if 
not all, instances the observers have not ascertained whether the ants 
are nesting in an invisible root or stump far below the surface of the 
ground. 

The natural food of the ants consists largely of dead and live insects, 
honeydew obtained from plant lice or treehoppers, the juices of well- 
ripened fruits, sap of certain plants, and refuse. Although workers 
tend plant lice, no one has observed them fostering or cultivating the 
lice, as do some of our well-known species of Lasius and Acanthomyops. 
The ants feed on a wide variety of household foods such as sweets 
(honey, syrup, sugar, jam, preserves, jelly), raw and cooked meats, 
fruits (pears, apples, oranges), melons, cakes, and boiled eggs. 

The ant is inimical to man because of its habit of nesting in the 
wood of houses and other buildings, telephone and telegraph poles, and 
other wood or wood products ; because it feeds on household foods ; and 
because it annoys housekeepers by its presence in houses. One cor- 
respondent complained that a carpenter ant bit her arm while she was 



66 TECHNICAL BULLETIN 1326, U.S. DEPT. OF AGRICULTURE 

asleep and that a welt later resulted from the bite. She also stated 
that she had found one of the ants attached to the lip of her dog. 
Although this ant has no sting, the large workers can inflict a painful 
bite with their strong mandibles, and the wound can be aggravated by 
the injection into it of formic acid. 

During the warmer months of the year workers may invade houses 
from their nests outdoors in trees, logs, stumps, or other places. Quite 
often the ants make conspicuous trails on the lawn or soil in passing to 
and from their nest. Infrequently the ants are accidentally brought 
into houses on firewood stored in the basement. It appears quite 
definite that houses in the vicinity of trees, logs, or stumps suffer more 
from carpenter ant attack than nouses some distance from them, and 
that older houses are more frequently attacked than new ones because 
the woodwork in them may be in poorer condition. The ants seem to 
enter houses through faulty, decayed, or moist wood, and although 
their nest may begin there, it may extend into adjacent solid wood- 
work. Black carpenter ants may attack the woodwork of houses in 
various places but quite often they attack the beams, underpinnings, 
porch pillars, window casings, and external trim. The presence of a 
nest in a house can often be detected by the fine sawdust and fragments 
of insects thrown out by the ants from small holes in the woodwork. 
Simeone states that laboratory studies and numerous observations of 
carpenter ant damage to buildings suggests that the ants prefer to 
nest in moist wood. Attempts to induce the ants to colonize in wood 
containing less than 15 percent moisture were generally unsuccessful. 
He further remarks that the moisture content in well-constructed, heat- 
ed structures should ordinarily vary from 6 to 10 percent, and prop- 
erly air-seasoned lumber, from 12 to 15 percent; wood kept at this 
moisture equilibrium should be free from carpenter ant attack. Ex- 
cessive moisture content of wood is therefore to be prevented by keep- 
ing it from direct contact with the ground, from seepage, from con- 
densation, or poor ventilation. Workers frequently (but not always) 
forage at night, and for that reason the housekeeper may fail to see 
them. In their search for moisture, the ants may appear in the bath- 
room, the kitchen sink, and lavatories. Workers will even crawl on to 
dishrags or towels in their quest for moisture. Black carpenter ants 
occasionally nest in houses in such unusual places as trunks, or chests 
of drawers stored in the attic or basement. They have also been re- 
ported occurring in a roll of waxed paper. 

Friend and Carlson, in studying damage by these ants to chestnut 
poles in Connecticut, found that 10 percent of the poles had to be re- 
placed each year because of the ants' nesting habits. At the time of 
their investigations, each replaced pole cost $30 to $35. Most of the 
damage occurred from ground level to about 6 feet above ground, and 
consisted of both longitudinal and radial injury, the latter being the 
most serious. They were of the opinion that nests originated in de- 
cayed spots, deep checks, knot holes, or other types of injury, and that 
the solid wood was not attacked until the colony became large. 
Snyder, however, found that sound chestnut poles set in dry ground 
in woodlands were damaged by the ants to some extent, but he did not 
elaborate on the nature of the wood at the ants' point of entry. 



HOUSE-INFESTING ANTS OF THE EASTERN UNITED STATES 67 

The hardiness of these ants is almost beyond belief. Fielde found 
that 50 percent of the ants survived for 70 hours while submerged in 
water, but none survived 95 hours of this treatment. A beheaded 
worker was kept alive for 41 days. McCook reported the ants capable 
of surviving 48 hours of freezing on ice, and Weber has stated that 
although this species was driven out, or almost exterminated from 
certain drought areas in the 1930's, the ants soon repopulated the areas 
after the return of normal conditions. 

Although black carpenter ants are usually not regarded as being 
aggressive or vicious, especially in their relation to other species, Kau, 
the author, and others have witnessed pitched battles between what 
was thought to be two alien colonies of this species, resulting in in- 
numerable dead and injured ants that had been cut to pieces by the 
strong mandibles of other workers. One could find numerous speci- 
mens with a gaster, head, or part or all of the antennae and legs com- 
pletely cut off, as if someone had used a pair of sharp scissors. 

A native ant such as the black carpenter ant, which nests in trees, 
logs, stumps, poles, and other wood or wood products, is expected to 
be distributed by commerce. England and New Zealand especially, 
have reported the introduction of black carpenter ants. No doubt 
the species frequently has been carried into many countries by com- 
merce, but so far as I am aware, it has failed to establish itself. 

The ants are parasitized by at least two species of flies belonging to 
the family Phoridae. One of the best known is Apocephalw per- 
gandei Coquillett. The larva of pergandei feeds on the interior of 
the head of a living ant until the ant succumbs from the attack. As 
Wheeler so aptly put it, the larva causes the ant to "literally lose its 
head." The parasitic fungi Cordyceps unilateralis (Tulasne), Des- 
m/idiospora myrmecophila Thaxter, and Beauveria globulifera Speg. 
attack this ant. An ant killed by C. unilateralis bears a conspicuous 
stalk on which is borne an enlarged fruiting body. The fruiting body 
of lateralis is attached to the side of the stalk. None of these parasites, 
insect or fungus, seem to exert any appreciable effect in controlling the 
population of the black carpenter ant. 

References: McCook, 1876, pp. 277-289; .McCook, 1883, pp. 303-307; Fielde, 
1904, pp. 170-174; Pricer, 1908, pp. 177-218; Davis, 1908, pp. 10-12; Snyder, 
1910, p. 8; Malloch, 1912, pp. 411-529; Mitchell and Pierce, 1912, pp. 67-76; 
Gaige, 1914, pp. 25-28; Graham, 1918, pp. 32-40; Davis and Bequaert, 1922, 
pp. 22-23; Bequaert, 1922, pp. 389-401; Wheeler, 1926, pp. 10, 83, 85, 131, 188, 
189, 191, 208, 393, 407, 417, 419, 422, 453; Donisthorpe, 1927, pp. 401, 403; Rau, 
1934, p. 215 ; Friend and Carlson, 1937, pp. 913-929, figs. ; Friend, 1942, pp. 12, 14 ; 
Townsend, 1945, pp. 1-27; Gregg, 1946, p. 753 (footnote) ; Creighton, 1950, p. 16; 
Simeone, 1954, pp. 1-19 ; Van Pelt, 1963, p. 212. 

Camponotus ferrugineus (Fabricius) 

Red carpenter ant. The selection of the ESA-approved common 
name "red carpenter ant," for this species was unfortunate, in my 
opinion, since it may cause confusion with Camponotus noveboracensis 
(Fitch) , which is largely red (thorax, petiole) . A name more closely 
agreeing with the scientific name and coloring would have been the 
"rust-colored carpenter ant." This native species ranges from Ne- 
braska to New York, south to Georgia. 



68 TECHNICAL BULLETIN 1326, U.S. DEPT. OF AGRICULTURE 




Figure 36. Camponotus ferrugineus (Fabricius), red carpenter arrt, lateral view of worker. 

Taxonomic Characters 

/Subfamily and generic characters: Same as for pennsylvanicus. 
Specific characters: Workers approximately the same size as those of 
pennsyTwanicus, about 6-13 mm. long. Distinguished largely by color- 
ing and pilosity. Most of the thorax (usually mesothorax and epino- 
tum), petiole, base of gaster, and much of the legs yellowish fer- 
ruginous; remainder of body and legs blackish or mack (allowance 
must be made for considerable variation) . Head, thorax, and gaster 
opaque or subopaque. Hairs and pubescence deeper, or more golden 
yellow than those of pennsylvanicus, especially on gaster. Pubescence 
on gaster dense and appressed. Near apex of each middle and hind 
tibia, a short row of graduated bristles. 

Biology and Economic Importance 

This species closely blankets the distribution of Camponotus penn- 
sylvanicus, but is apparently not as widely distributed or as common. 
It is a low-altitude form (Cole did not find any nests in the Great 
Smoky Mountains of Tennessee above an altitude of 4,200 feet) that 
lives by preference in wooded areas; here the ants normally nest in, 
and beneath, well-rotted logs and stumps, their galleries often extend- 
ing for considerable distances into the soil. They also nest in dead, 
standing trees. Colonies may range from less than a hundred to con- 
siderably more than 3,000 individuals. Males and winged females are 
produced only by large colonies several years old, but it appears that 
there is only one reproductive female per colony. Males and females 
produced during one year can overwinter in the parental nest and make 
their nuptial flights the following year. A new colony is established 
by a single fertile female, unaided by workers. Workers feed on small 
insects, honeydew, the juice of fruits, and the sap of plants. Workers 
tend honeydew-excreting insects, but there is no evidence that they 
foster or disseminate them. C. ferruginous, although similar to penn- 
sylvanicus in many of its habits, is apparently not the major house 
pest or potential wood-destroying species that pennsylvanicus is, al- 
though Graham states that both pennsylvanicus and ferrugin&uis have 



HOUSE-INFESTING ANTS OF THE EASTERN UNITED STATES 69 

done considerable damage to standing white cedar in Minnesota by 
gaining entrance through a decayed or wound spot and mining out 
both faulty and sound wood for considerable distance. 3 
. My unpublished records indicate that although workers, males, and 
females, singly or in various combinations, have been observed in 
houses, only in a few instances have actual nests been located, and 
then only in faulty or moist wood, especially that which has been sub- 
jected to water damage. I have no record of household foods eaten by 
these ants ; nor have I been able to locate any published information 
on the subject. 

References: Pricer, 1908, pp. 177-218; Graham, 1918, pp. 32^40; Wesson and 
Wesson, 1940, pp. 90, 103; Cole, 1940, pp. 30, 86; Gregg, 1946, p. 753 (footnote) ; 
Brown, 1950, pp. 158-161. 

Camponotus abdominalis ftoridanus (Buckley) 

Florida carpenter ant. A native ant which ranges from Alabama 
and Horn Island (off the coast of Mississippi) east to North Carolina 
and Florida. This subspecies, although widely distributed in Florida, 
apparently does not occur very far inland in the other States from 
which it has been reported. It is one of the common, if not the most 
common, Camponotus species in Florida. C. abdominalis (F.^ is a 
well-known neotropical ant, which is so highly variable that it has 
produced many subspecies. 

Taxonomic Characters 

/Subfamily and generic characters: Polymorphic. Antenna articu- 
lated at a considerable distance from the posterior border of the cly- 
peus. Antennal fossa not touching the posterior border of the clypeus. 
Antenna 12-segmented, without a club. Scape flattened basally ; very 
much broadened throughout except basally. Frontal carinae not placed 
close together, lyrate in shape. Clypeus largely in the form of a lobe, 

' Both Gregg and the author think that Graham may have confused penntylvanicu* and 
ferruginens with Camponotus herculeanus (L.) and C. noveboracenia (Fitch). 




Figure 37. Camponotus abdominalis floridanus (Buckley), Florida carpenter ant, lateral 

view of worker. 



70 TECHNICAL BULLETIN 1326, U.S. DEPT. OF AGRICULTURE 

the anterior border of which is broadly but weakly emarginate. Cly- 
peus with a rather distinct carina. Abdominal pedicel composed of 
a single segment, the petiole. Cloacal orifice terminal, circular, sur- 
rounded by a fringe of hairs (fig. 48, co) . Sting lacking. Workers 
capable of emitting a distinct formic acid odor. Specific characters: 
Large ants, workers 5.5-10 mm. long. Scape with scattered suberect 
or erect hairs. Head subopaque or opaque ; thorax, petiole, and gaster 
shiny. Head reddish, thorax and petiole yellowish or yellowish-red, 
scape and gaster blackish or black, quite often base of first gastric 
segment yellowish or yellowish-red. Legs with numerous suberect 
hairs which, although long, are shorter than those on body. Body 
with abundant, long, suberect or erect yellowish hairs. In some lights 
gaster has grayish or violaceous cast. Species readily distinguished 
by its characteristic color and pilosity. 

Biology and Economic Importance 

This subspecies commonly nests in the ground beneath objects, in 
dead branches of trees, and in and beneath rotting logs and stumps. 
However, the ants are highly adaptive in their nesting habits and in 
their choice of ecological habitats. Colonies are moderate to large in 
size. In Florida, nuptial flights apparently occur most commonly 
from June to August. New colonies are founded by a single fertilized 
female, independent of aid from workers. It is normal for a colony 
to have a single reproductive female. Under natural conditions the 
ants feed largely on small insects and honeydew, and may eat both 
live or dead insects. They tend plant lice, mealybugs, and scales. 
Workers are active both day and night. The aggressive, pugnacious 
habits of the workers have earned for them the common name "bull 
dog" ants. While on some occasions it definitely appears that the ants 
have invaded houses from outdoors, there is not the slightest doubt 
that they also nest within the structure of buildings. On several oc- 
casions, correspondents have reported them nesting in and damaging 
the woodwork of porches, roofs, kitchen sinks, and paneling. The 
ants feed on such household foods as molasses, honey, and liver. Work- 
ers are also known to disrupt colonies of bees by plundering their 
hives for food or living quarters. This ant undoubtedly ranks as one 
of the most important house-infesting ants in Florida. 

References: Wheeler, 1932, p. 15; Schneirla, 1944, pp. 3-1; Creighton, 1950, 
pp. 395-396; Smith, 1950, pp. 299-300; Van Pelt, 1958, pp. 46-19. 

Camponotus caryae discolor (Buckley) 

A native ant, Camponotus caryae discolor (Buckley) ranges from 
Kansas and Iowa to Ohio, south to Texas and Florida. The subspecies 
is probably most common in the lower Mississippi Valley region or 
the Central States, but appears to be much less generally common than 
Camponotus rasttis Wheeler and C. nearcticus Emery. G. caryae 
(Fitch) is a North American ant whose distribution appears to be 
largely eastern. It is thought to have produced at least one or more 
valid subspecies. 



HOUSE-INFESTING ANTS OF THE EASTERN UNITED STATES 71 




Figure 38. Campono/us ca/yae discolor (Buckley): a, Lateral view of worker; b, frontal 
view of clypeus showing the emargination or impression at the middle of its anterior 
border. 



Taxonomic Characters 

Siik family and generic characters: Polymorphic. Antenna 12-seg- 
mented, without a club. Aritennal fossa not touching the posterior 
border of the clypeus. Middle of the anterior border of the clypeus 
with a distinct but narrow emargination or impression ( fig. 38,6 ). Cly- 
peus weakly carinate or almost ecarinate. Each middle and hind tibia 
without a row of bristles on their flexor surface. Abdominal pedicel 
composed of a single segment, the petiole. Cloacal orifice terminal, 
circular, surrounded by a fringe of hairs (fig. 48,c0) . Sting lacking. 
Workers capable of emitting a distinct formic acid odor. Specific char- 
acters : Workers 3.5-7.5 mm. long. Head, thorax, and petiole yellowish 
red or reddish, the gaster blackish or black. Anterior portion of head, 
especially cheeks and clypeus, punctulate, subopaque; clypeus and 
especially cheeks with elongate, piligerous f oveolae. Closely resembles 
Camponotus rasilis Wheeler but can be distinguished from that spe- 
cies by the peculiarly sculptured and more subopaque anterior portion 
of head and by the short, erect hairs of clypeus and cheeks. Body of 
discolor is usually lighter, more yellowish, and smaller than that of 
rasilis. 

Biology and Economic Importance 

The biology of this ant is so similar to that of rasilis that it hardly 
requires further comment here. On several occasions the ants were 
collected under conditions that clearly indicate they were nesting in 
houses. There they are potentially capable of nesting in preformed or 
natural cavities, or in rotting or faulty wood. It is doubtful that their 
excavating activities could cause any appreciable damage because of 
the small size of the ants, and the small colonies. I have no records of 
household foods being infested by the workers. 

References: Mitchell and Pierce, 1912, pp. 75-76; Wesson and Wesson, 1940, p. 
103 ; Hess, 1958, pp. 47-48, 56, 58-59. 



72 TECHNICAL BULLETIN 1326, U.S. DEPT. OF AGRICULTURE 

Camponotus nearcticus Emery 

A native species, nearcticus ranges from North Dakota to Ontario, 
south to Colorado and Florida. Creighton states that the species has 
a discontinuous distribution, and occurs from British Columbia to 
California and eastward to Idaho. Unfortunately, from 1917 to 1940 
the species was confused in our literature with caryae (Fitch) , a much 
less common species but one with somewhat similar habits arid appear- 
ance. 
Taxonomic Characters 

/Subfamily and generic characters: Same as for caryae discolor. 
Specific characters: Workers 4.5-7.5 mm. long. Clypeus with rather 
large foveolae which bear suberect or erect hairs : f oveolae of cheeks 
smaller and more numerous but not bearing suberect or erect hairs. 
Scape without erect hairs, except at apex. Legs entirely or almost 
entirely without hairs except at apices of segments. Petiolar node 
narrow in profile, the anterior surface moderately convex, posterior 
surface flattened. Body pubescence sparse, scattered, closely appressed 
and not concealing the surface; most abundant and easily seen on 
gaster. Body of typical form blackish or black but color subject to 
considerable variation ; occasionally some of the segments or areas of 
body largely reddish or brownish. Body shiny, the head least, the 
gaster most. Typical form easily recognized by its black and rather 
shiny body, emarginate clypeus, and lack of erect hairs on cheeks. 

Biology and Economic Importance 

C. nearcticus is not only one of the most widely distributed species 
of the subgenus Myrmentoma discussed here, but also one of the most 
common. The ants of this subgenus, which are smaller (3-7 mm.) 
than most Camponotus, are distinguished especially by the emargina- 
tion or impression at the middle of the anterior border of the clypeus. 
Most of the known forms are eastern. 

Under natural conditions nearcticus forms small colonies of less 
than a hundred to several hundred individuals in dead twigs and 
branches of trees, in or beneath the bark of dead and live trees, in 




Figure 39. Camponotus nearcr/ci/i Emery, lateral view of worker. 



HOUSE-INFESTING ANTS OF THE EASTERN UNITED STATES 73 

insect galls, pine cones, beneath the bark of logs and stumps, hollow 
stems of plants, and in wooden posts. The species will also accept hol- 
low wooden traps designed for certain wasps. Nests have been noted 
especially in such trees as pine, oak, and hickory. Although mainly a 
lowland form, the species has been collected at altitudes of approxi- 
mately 6,000 feet. It is not known when the males and winged females 
are produced, but there is abundant evidence to indicate that these 
forms overwinter in the parental nest ; they no doubt make their nup- 
tial flights the following year. Kannowski states that recently mated 
females seek cavities in which to start new colonies. These females 
establish their nest independently of aid from workers. The timid, 
hard-to-capture workers crawl over trees and shrubs in search of 
honeydew for food, a diet which is largely supplemented by dead in- 
sects. They forage both day and night. On numerous occasions I 
have received all castes of this ant from houses, where they have been 
found nesting in the woodwork, especially in the roofing ; the owners 
of such premises have especially mentioned the moistness of the nesting 
sites. Since housekeepers have seldom complained of the ants infest- 
ing household foods, I assume the ants are of minor importance in this 
respect. 

References: Wheeler, 1905b, pp. 402-403; Smith, 1924, p. 125; Cole, 1940, pp. 
15, 29, 83 ; Van Pelt, 1958, pp. 44-45 ; Kannowski, 1959, pp. 119-120, 134. 

Camponotus rasilis Wheeler 

A native species which ranges from Nebraska south to Texas, South 
Carolina, and Florida. The species is apparently most common in the 
Gulf Coast States where it is more abundant than either nearcticus or 
caryae discolor. 

Taxonomic Characters 

Subfamily and generic characters: Same as for caryae discolor. 
Specific characters : Workers 4-9 mm. long. Cheeks and clypeus with 
distinct but not unusually large or coarse f oveolae ; f oveolae on cheeks 




Figure 40. Camponotus rasilis Wheeler, lateral view of worker. 



74 TECHNICAL BULLETIN 1326, XJ.S. DEPT. OF AGRICULTURE 

not bearing short, erect, or suberect hairs. Gaster smooth and shiny, 
head and thorax shagreened and more subopaque, head, in certain lights 
somewhat shiny. Workers of typical species have yellowish red or 
reddish head, thorax, and petiole, and blackish or black gaster. Occa- 
sionally the base or much of the first gastric segment is lighter than 
the remainder of the gaster. Femora and tibiae of legs lacking or 
almost lacking erect hairs. Bears superficial resemblance to caryae 
discolor but can be distinguished from that species by less coarse, sub- 
opaque cheeks and clypeus, and especially by lack of short, erect hairs 
arising from foveolae of cheeks. 

Biology and Economic Importance 

The ants form small colonies of only a few hundred individuals 
They nest in galleries made by borers in twigs and branches of trees; 
in insect galls, particularly those of Disholcaspis cinerosa (Bassett) 
on oak ; in cavities in the stalks of plants ; under the bark of trees ; in 
logs and stumps, wooden posts, and in houses. A new colony is 
founded by a single fertilized female, unaided by workers. It is 
normal for males and winged females produced in one year to over- 
winter in the parental nest and make their nuptial flights the next 
year. The natural food of rasilis workers is largely the honeydew 
excreted by scale insects and plant lice on the surface of leaves and 
twigs of trees and plants. This diet is largely supplemented by the 
dead bodies of insects. The species frequently nests in the woodwork 
of houses, although it may also invade houses from outdoors. Quite 
often workers invade houses at night. It is assumed that the ants start 
their nest in faulty wood or preformed cavities. On one occasion a 
colony was found nesting in the roller of a window shade. Because of 
the small size of the ants and their colonies, it does not seem possible 
for them to do any significant damage to woodwork. Workers fre- 
quently feed on such household food and drink as breads, fruits, cakes, 
syrup, sugar, jam, and coca cola. The ants appear to show a pref- 
erence for sweets. 

References: Wheeler, 1910b, pp. 22T-228; Smith, 1924, p. 126; Smith, 1950, pp. 
297-298 ; Hess, 1958, pp. 48^9, 56, 58-59. 

Paratrectdna longicornis (Latreille) 

Crazy ant. This introduced species, apparently of African or, more 
likely, Oriental origin, has become widely disseminated by commerce 
to various parts of the World. It is frequently intercepted in plant 
quarantine. The species is well established in many towns and cities 
of the Gulf coast region, especially in Florida. Farther north and 
inland it is more sporadically distributed, occurring in apartment 
buildings, hotels, and greenhouses. The crazy ant gets its name from 
the worker's habit of darting here and there in a jerky, haphazard 
manner, as if lacking a definite sense of direction. 

Taxonomic Characters 

Subfamily and generic characters: Monomorphic. Antenna 12- 
segmented, without a club. Scape extraordinarily long, apex sur- 
passing posterior border of head by at least one-half the length of the 



HOUSE-INFESTING ANTS OF THE EASTERN UNITED STATES 75 




Figure 41. Paratrechina /ong/cornrs (Latreille), crazy ant, lateral view of worker. 

scape. Antennal fossa inserted very close to posterior border of 
clypeus, lacking the width or less of the fossa of touching the posterior 
border of the clypeus. Eye large, strongly convex, placed closer to 
base of mandible than to posterior border of head. Clypeus sub- 
carinate. Maxillary palpus long, 6-segmented. Legs extraordinarily 
long. Base of gaster with an impression. Base of gaster angulate on 
each side of impression (viewed from above). Abdominal pedicel 
. composed of a single segment, the petiole. Cloacal orifice terminal, 
circular, surrounded by a fringe of hairs (fig. 48,co). Sting lacking. 
Integument soft and flexible. Specific characters: Workers 2.2-3 mm. 
long. Body strikingly slender, with extraordinarily long antennae 
and legs. Body with long, coarse, well-scattered, suberect to erect, 
grayish or whitish hairs. Suberect or erect hairs normally absent from 
scape. Legs with shorter suberect hairs. Head, thorax, petiole, and 
gaster dark brown to blackish or black, ground surface with peculiar 
gray to violaceous luster or sheen. 

Biology and Economic Importance 

The slender-bodied, long-legged worker is capable of moving rapidly, 
and even jumping, according to some observers. Wroughton states 
that the ant is endowed with a keen sense of smell, which enables it to 
locate food quickly. The species is highly adaptable, living in both 
very dry and rather moist habitats, and nesting in such places as 
trash, refuse, cavities in plants and trees, rotten wood, and the soil 
under objects. Colonies are moderate-sized to populous. Because no 
intensive work has been done on the biology of longicornis, many de- 
tails of its life history are lacking. Workers are almost omnivorous. 
They feed on both live and dead insects, seeds, honeydew, fruits, plant 
exudates, and many household foods. They obtain the honeydew by 
tending plant lice^ mealybugs, and scales. Pimentel states that in 
Puerto Rico, workers killed larvae and adults of Musca domestica 
(Linnaeus), GaUitroga maoellaria (Fabricius), Sarcophaga sp., and 
others. The workers oilongicornis and those of several other species 
of ants destroyed 91 percent of the potential fly population. Fox and 
Garcia-Moll (1961) have observed workers of this ant species attack- 
ing larvae of the Oriental rat fie&.Xenopsylla cJieopis (Rothschild) 
under laboratory conditions, and suggest that the ants may be impor- 
tant in reducing the population of this flea under natural conditions. 



76 TECHNICAL BULLETIN 1326, U.S. DEPT. OF AGRICULTURE 

Workers are known to gather small seeds of such crops as lettuce and 
tobacco from seed beds. In sections of our country subject to very cold 
weather or pronounced winters, the ants nest in apartment and hotel 
buildings, where they are potential pests the year around. Workers 
feed on many household foods such as meats, grease, sweets, fruits, and 
vegetables, and on liquids, such as fountain syrup and soft drinks. 
The ants seem especially fond of sweets. It was reported that one soda 
fountain in Florida discontinued business because of the ravages of 
this pest. 

References: Wroughton, 1892a, pp. 41-i2; Phillips, 1934, pp. 18-19; Smith, 
1936, pp. 869-870; Smith, 1950, pp. 289-290; Pimentel, 1955, pp. 28-30; Fox and 
Garcia-Moll, 1961, pp. 1065-1066. 

Paratrechina (Nylanderia) spp. 

This heading includes mostly native species, with a few that have 
been introduced. Ants of this subgenus are widely distributed over 
the hot and temperate regions of the World. Their distribution in 
the United States is still poorly known ? but better understood east of 
100 longitude. Males and their associated genitalia afford the only 
reliable means of identifying these ants to species. The species can 
seldom be identified on the basis of workers alone; however, should 
the reader wish to attempt such determinations, he is referred to 
Creighton (1950, pp. 404, 405-^10) . 

Taxonomic Characters 

Subfamily and generic characters: Same as for longicomis except 
as follows: Length 2.24 mm. Apex of scape exceeding posterior 
border of head by at least one-fifth or more of the length of the scape. 
Scape of most species usually with noticeable, prominent, suberect to 
erect hairs. Antennal fossa very close to, or touching, posterior border 
of clypeus. Eye well developed. Clypeus carinate or subcarinate. 
Thorax somewhat stout. Mesonotum more or less distinctly separated 




Figure 42. Parafrechina (Nylanderia) sp., lateral view of worker. 



HOUSE-INFESTING ANTS OF. THE EASTERN UNITED STATES 77 

from adjacent regions of throax by sutures or impressions. Mesoepino- 
tal suture very distinct dorsally and bearing within this region a pair 
of rather prominent spiracles. Base of epinotum usually shorter than 
declivity. Petiolar node usually inclined. Base of gaster with a dis- 
tinct impression, on each side of which the gaster is more or less angu- 
late ('best seen from above). Legs with rather long, suberect to erect 
hairs. Pubescence on body rather short, closely appressed, and often 
fairly dense, especially on gaster. Body with scattered, long, coarse, 
suberecet to erect hairs that vary from light yellowish to dark brown, 
depending upon the species. Body commonly shiny, often depending 
upon ,the light in which the body is viewed. Body color usually yel- 
lowish, brown, or blackish. 

Biology and Economic Importance 

Most of these ants are native species which normally nest outdoors. 
A few introduced species are capable of living outdoors in the extreme 
Southern States, but can exist only in greenhouses or heated build- 
ings father north. Our native species, especially, are potential house 
pests. Workers of most species are mud-mannered, nonagressive, 
rather active ants, capable of foraging both day and night. Ants of 
this subgenus form small colonies of only a few hundred individuals 
in diverse dry-to-moist habitats ; they occur in beaches, fields, meadows, 
and woods. The ants are mainly lowland forms, none of our Eastern 
States species ranging above 5,000 feet. The ants may nest in the ex- 
posed soil, or under the cover of objects, in rotten wood, under the 
bark of logs and stumps, in twigs, or in plant cavities. No complete 
biological studies have been made of any of the species. Males and 
winged females of the native species are known to overwinter in the 
parental nest and make their nuptial flights the following year. A 
newly fertilized female is capable of establishing a colony unaided by 
workers. Workers tend plant lice, mealybugs, and scale insects for 
honey dew, and also feed on both live and dead insects and the juices 
of fruits. They feed on a wide variety of household foods such as 
sweets, pies, fruits, fruit juices, fountain and table syrup, and meats. 
They are especially fond of sweets, and in some localities have been 
called "sugar ants" because of their fondness for this food. They may 
invade houses and stores from outdoors, but also nest within the struc- 
tures of buildings. They are not capable of causing any appreciable 
damage to woodwork or masonry because of their small size and small 
numbers, but they can be very annoying to housekeepers and store 
owners. Although not numerous in species, the ants are sometimes ex- 
tremely numerous in colonies and individuals, especially in certain 
areas. At least one species in this subgenus may possibly be an inter- 
mediate host of the poultry tapeworm Raillietina tetragona (Molin) ; 
workers of an undetermined species have been seen carrying gravid 
segments of that tapeworm into their nest. 

References: Wheeler, 1905b, pp. 374, 390-393 ; Phillips, 1934, pp. 18-19; Dennis, 
1938, pp. 295, 306 ; Case and Ackert* 1940, pp. 393-395 ; Cole, 1940, pp. 14-15, 
66 ; Hess, 1958, pp. 54-58, 62-63. 



78 TECHNICAL BULLETIN 1326, U.S. DEPT. OF AGRICULTURE 

Prenolepis imparts (Say) 

A name commonly applied to this species is the "false honey ant." 
This native species ranges at least from Nebraska to Ontario and south 
to Texas and Florida. 

Taxonomic Characters 

Subfamily and generic characters: Monomorphic. Antenna 12-seg- 
mented, without a club. Apex of scape surpassing posterior border 
of head by approximately one-half length of scape. Antennal fossa 
extremely close to or touching posterior border of clypeus. Eye prom- 
inent, convex, placed closer to posterior border of head than to base 
of mandible. Clypeus subcarinate. Mandible with oblique masti- 
catory border bearing 5 or 6 stout teeth. Maxillary palpus 6-seg- 
mented, usually long. Thorax small, slender, divided into two parts 
by a remarkably strong constriction in the mesonotum ? which causes 
this region to appear subcylindrical. A pair of prominent spiracles 
occurs dorsally in the constriction. Abdominal pedicel composed of 
a single segment, the petiole. Cloacal orifice terminal, circular, sur- 
rounded by a fringe of hairs (fig. 48,co). Sting lacking. Base of 
gaster with a strong impression ; seen from above, base of gaster meets 
each side in a decided angle. Integument soft, flexible. Specific 
characters: Workers 2-4 mm. long. Body hairs whitish or pale yel- 
lowish, suberect to erect, more abundant on head and gaster than on 
thorax, apparently longest on gaster. Scape with abundant, fine, ob- 
lique hairs or pubescence. Legs with fine, closely appressed pubes- 
cence; almost free of suberect or erect hairs except basally. Body 
smooth and shiny. Body color variable, ranging from pale castaneous 
to piceous brown or blackish, head and thorax often lighter than 
gaster. Keadily recognized by the characteristic subcylindrical meso- 
notum, and the smooth, shiny body. 

Biology and Economic Importance 

This ant normally constructs its nest in the soil, seldom under the 
cover of stones or other objects. It nests by preference in moist clay 
or loamy soils in well-shaded locations such as woodlands. Van 
Pelt has collected occasional colonies in the Blue Eidge Mountains at 
altitudes of between 3,500 and 5,000 feet. Exteriorly, the nest has a 




Rgure 43. Prtnolepii imparit (Soy), lateral view of worker. 



HOUSE-INFESTING ANTS OF THE EASTERN UNITED STATES 79 

single central opening surrounded by a more or less circular crater of 
characteristic earthen pellets. The nest is usually 18 to 51 inches deep 
and has a single gallery leading below, from which there extends in 
linear sequence about 6 to 40 lateral chambers, thus forming a rather 
compact, well-defined nest. Colonies are rather small, seldom con- 
taining over a few thousand individuals. Brood production takes 
place from middle to late summer, but no brood is overwintered. 
During the winter an old, characteristic colony will contain a single 
reproductive female, numerous workers, and males and winged fe- 
males. In early spring, usually March to April, the overwintering 
males and winged females mate their nuptial flight. Most of the 
mating, however, appears to take place on the ground. As far as I 
am aware, this is the first species of the season to make its nuptial 
flight; it could therefore be considered a harbinger of spring! A 
new colony is founded by a newly fertilized female, which discards 
her wings and seeks a crevice in the ground all by herself. Workers 
forage at night, during cool or cloudy days, or during rains, working 
at lower temperatures (40 to 65 F.) than any of our other species 
of ants. In fact, they frequently appear outside the nest when the 
soil is frozen. Workers are mild-mannered, nonagressive ants. Few 
ants exceed imparis in their love for honeydew. Workers assiduously 
tend plant lice, scale insects, and treehoppers, none of which, how- 
ever, are kept or fostered by imparis. Workers often become so 
engorged with honeydew that their gasters are distended like bal- 
loons, and they walk with difficulty. In the possession of a greatly 
distended gaster, they bear a striking resemblence to our true honey 
ants, Myrmecocystus spp. 

They feed on live and dead insects, the juices of well-ripened or de- 
caying fruits, the sap or juice extracted from flower buds, or the tender 
growth of certain plants, and on the germinating seeds of long leaf 
pines. Although workers commonly invade houses from outdoors, 
there is evidence that, in some cases at least, the ants nest inside, since 
on numerous occasions winged females and males have been collected 
inside houses from January to March. The ants are incapable of 
structural damage, but they can be a considerable annoyance to house- 
keepers. Workers feed on such household foods as sweet corn, corned 
beef, meats, cakes, breads, sugar, honey, syrup, watermelon, and 
fruits. The ants seem to be especially fond of sweets, and may be 
economically important when workers search for honey in weakened 
beehives. They can damage roses and oranges by gnawing into the 
flower buds for the sap or ]uice. Workers have been used by blue jays 
in "anting" (see Glossary, p. 93). Experimental tests by Smith and 
Weiss have shown that this ant can transmit azalea flower spot, 
Orulinia azalea Weiss. 

References: Wheeler, 1930, pp. 1-15; Smith and Weiss, 1942, p. 42; Talbot, 
1943, pp. 31-44; Talbot, 1945, pp. 506-507; Hess, 1958, pp. 52-53, 55-57, 59, 63: 
Van Pelt, 1963, p. 213. 



749-386 O 05 6 



80 TECHNICAL BULLETIN 1326, TJ.S. DEPT. OF AGRICULTURE 

Lasius alienus (Foerster) 

Cornfield ant. This species. has a discontinuous distribution in 
North America. According to Wilson, it ranges from British Colum- 
bia to northern California, and from North Dakota to Nova Scotia, 
south to Arkansas and northern Florida. The species also occurs in 
the mountains of southern Arizona. L. alienus appears to be sparse 
or absent in the southern Rockies and Great Basin, and is rare or 
locally distributed in the Gulf Coast States. This is the form that 
has passed in earlier American literature under the varietal or sub- 
specific name americanus Emery. In America, it has been frequently 
confused with Lasius neoniger Emery (p. 81), which it resembles so 
closely that one must be very cautious in accepting literature records 
without knowing the full history. 

Taxonomic Characters 

Subfamily and generic characters: Workers monomorphic. An- 
tenna 12-segmented, without a club. Antennal fossa very close to, or 
touching, posterior border of clypeus. Frontal carinae not placed 
close to each other. Eye well developed, located closer to posterior 
border of the head than to base of mandible. Ocelli, if present, small 
and indistinct. Maxillary palpus long, 6-segmented, terminal seg- 
ments of approximately the same length. Mesoepinotal impression 
well defined, bearing a pair of distinct spiracles. Declivity of 
epinotum more than twice as long as base of epinotum. Abdominal 
pedicel composed of a single segment, the petiole. Petiolar node 
scalelike, thin or narrow in profile, and either vertical or not strongly 
inclined. Cloacal orifice terminal, circular, surrounded by a fringe 
of hairs (fig. 48,co) . Sting lacking. Integument soft and flexible. 
Workers active, not light-avoiding, and capable of emitting a strong 
formic acid odor. Specific characters: Workers approximately 2-2:5 
mm. long. Penultimate and terminal basal teeth of mandible sub- 




Figure 44. Los/us alienus (Foerster), cornfield ant, lateral view of worker. 



HOUSE-INFESTING ANTS OF THE EASTEKN UNITED STATES 81 

equal in size, the gap between them of about the same area as terminal 
tooth, constant in shape. Middle of anterior border of clypeal lobe 
forming an even, broad, parabolic curve. Scape exceeding, by ap- 
proximately one-fifth its length, the posterior border of head. Eye 
large, usually with about 16 ommatidia in its greatest diameter. 
Antennal scapes and tibiae either without suberect or erect hairs, or 
more commonly with less than 10 each. Body color brown to very dark 
brown, approaching blackish. 

Biology and Economic Importance 

L. alienus and L. neoniger are similar in many of their habits, but 
not especially in their habitats. Wilson states that in North America 
alienus has a predilection for well-shaded woodlands, where it nests 
in rotting logs and stumps and under stones. L. neoniger, on the other 
hand, prefers open haoitats (for further details see p. 82). The 
ranges of the two species frequently overlap in open woods and the 
borders of forests. Van Pelt has found colonies of (Menus abundant 
in the Blue Ridge Mountains at 5,000 feet, common at 6,000 feet, and 
occasional at 6,100 to 6,500 feet. The individuals composing a nest 
are moderately to very, numerous. They are quite similar to neoniger 
in their method of establishing colonies, and in the growth of colonies. 
Males and winged females occur in nests from midsummer to fall, the 
nuptial flights usually taking place during August and September. 
In Europe, a reproductive female was kept in an artificial nest for 9 
years (until she died), and during that time she produced a small 
brood of workers each year. In North America it is quite likely that 
this common species or Lasius is host to one or more temporary ant 
parasites belonging to Lasius (Chthonolasius) and Acanthomyops. 
For a discussion of how the parasitism may take place, see the remarks 
under L. umhratus (p. 85) . 

The feeding habits of alienus are almost identical to those of 
neoniger. Like the latter species, the ants eat both dead and live 
insects, gather nectar from the floral and extrafloral nectaries of 
plants, tend honeydew-excreting insects, and foster and transport cer- 
tain subterranean plant lice from the roots of one plant to another. 
Workers may invade houses from outdoors in their search for food 
such as sweets and meats. The ants are also capable of nesting in 
houses, usually in faulty woodwork or masonry of the basement or 
lower sections. Although they are frequent house pests, the ants 
are seldom persistent. Individuals are frequently infected with the 
parasitic fungus Laboufbenia formicarwm Thaxter, as are those of 
neoniger (see p. 84) . 

References: Galge, 1914, pp. 17-19; Donisthorpe, 1927, pp. 242-247; Wilson, 
1955, pp. 77-89; Kannowski, 1959, pp. 119-120, 135-136; Van Pelt, 1963, p. 213. 

Lasius neoniger Emery 

L. neoniger is a native species with a discontinuous distribution. 
According to Wilson, the main range is from Idaho to Quebec and 
Ontario, south to Florida, and south through Wyoming, Colorado, and 
New Mexico. The species also occurs in two small areas in eastern Cal- 
ifornia. It is not known to occur in the Pacific Northwest. In 
American literature this species has frequently been confused with 



82 TECHNICAL BULLETIN 1326, U.S. DEPT. OF AGRICULTURE 




Figure 45. Lasius neoniger Emery, lateral view of worker. 

alienus (= americanus Emery). In fact, Wilson considers that the 
work done by Forbes and associates on americanus applies largely, if 
not entirely, to neoniger. 

Taxonomic Characters 

Subfamily and generic characters: Same as for alienus. Specific 
characters : Workers of approximately the same size as alienus, 2-2.5 
mm. long. Antennal scapes and tibiae with numerous suberect or 
erect hairs. Anterior border of clypeal lobe obtusely angular medianly. 
Penultimate basal tooth of mandible markedly smaller than the two 
flanking teeth, or gap between penultimate and terminal basal teeth 
tends to be larger in area than the terminal basal tooth, and variable 
in shape. Color light to medium brown, rarely dark brown. 

Biology and Economic Importance 

Wilson states that in the eastern United States neoniger is frequently 
the dominant species of Lasius in lawns, cultivated fields, and grassy 
road strips. It is also a common ant in prairies, beaches, and sand 
dunes. The species nests almost exclusively in open areas, either 
beneath stones or in the exposed soil, where the presence of its nests is 
usually indicated by numerous but small craters of soil surrounding 
a central opening. The craters are often very abundant sometimes 
as many as 10 per square yard. A nest appears to be composed of a 
number of shallow, interconnected chambers (seldom more than 10 
to 15 inches deep), occurring over a rather large and irregular 
area. 

To my knowledge, no careful population counts have been made, 
but the adult population composing a large colony must amount to 
thousands. Present evidence indicates that there may be not more 
than one reproductive queen per colony, and that queenless colonies will 
accept a fertilized and dealate female from a nuptial flight. Nuptial 
flights ordinarily take place in late afternoon of the late summer and 
autumn months (August to October). The nights are usually, but 
not always, associated with storms and rains. Flight from some col- 
onies consist only of males; others, of a mixture of males and females. 



HOUSE-INFESTING ANTS OF THE EASTERN UNITED STATES 83 

Often immense numbers of individuals compose the flight, and the air 
may be literally "filled with ants." Tanquary believed that fertiliza- 
tion of the females took place in the nests prior to the nuptial flights, 
since he had never seen a male and female in copulation outside of the 
nest. After the flights it is common for the fertilized females to shed 
their wings and enter small self-made cavities in the ground. These 
queens remain alone in their chambers over winter, and do not normally 
lay eggs or start a new brood until the following spring. Successive 
broods are produced over an unknown number of years until at last 
the colony is large enough to produce males and winged females. 
Some colonies under certain conditions may become hosts of temporary 
parasites of other ants belonging to such genera as Lasius and Acan- 
thoim/ops. Gregg has found a mixed colony of L. umbratus and 
neomger, and Talpot has found a mixed colony of A. murphyi and 
neoniger. Talbot indicates that in ordinary summer weather workers 
of neoniger are largely nocturnal, their activity beginning to rise in the 
late afternoon, continuing through the night, and decreasing toward 
morning. 

Workers feed on both dead and live insects, the secretions of floral 
and extrafloral nectaries, and the honeydew excreted by plant lice, 
mealybugs, and other honeydew-excreting insects. Not only do these 
ants assiduously tend many different kinds of plant lice, but they also 
foster and transport certain subterranean plant lice. 

The relationship of this ant to the corn root aphid Anuraphis maidi- 
radicis (Forbes), is a classic example of mutualism. The ants store 
and care for the aphid eggs in their nest during the winter. In the 
spring when the aphids have hatched from the eggs, the ants carry 
them to the roots of certain grasses and weeds where the aphids remain 
and feed until the corn has grown enough to support the aphids ; the 
ants then carry them to the corn roots. In this relationship they 
protect, care for, and transport the aphids as the occasion may require. 
L. neoniger has the same general relationship to Anuraphis maulira- 
dicis on the roots of cotton. Orlob found that Lasius neoniger was of 
secondary importance in the spread of barley yellow dwarf virus by 
the aphid Schizaphis (Toxoptera) graminum (Rondani) on barley 
and oats. The ants were of importance in this role because they in- 
creased aphid populations largely by their protection of the plant lice 
from natural enemies, and also by furnishing the lice ideal quarters 
in which to breed. Orlob apparently thinks that the role of ants in 
bodily carrying infected lice from plant to plant is of little significance. 
L. neoniger is a frequent house invader, usually from outdoors, quite 
often following rains. These invasions are of short duration and lack 
the persistency of those of the Pharaoh ant, Argentine ant, or Pave- 
ment ant. Workers are general feeders on household foods, but seem 
to show a slight preference for sweets and meats. The ants can also 
be pests of some importance on golf courses where their innumerable 
earthen craters not only mar the appearance of the course, but also 
interfere with the game. Observers have noted workers and males of 
this ant being used by starlings, Sturnus vulgaris (Linnaeus), and 
grackles, Quiscalus quiscala (Linnaeus) , in "anting." Occasional indi- 
viduals of this ant, especially workers, bear fine, gravel-like objects 



84 TECHNICAL BULLETIN 1326, U.S. DEFT. OF AGRICULTURE 

externally on their bodies. Close examination under a microscope 
reveals them to be a parasitic fungus, Ldboulbenia formicarum Thax- 
ter. So far as I am aware, the fugus has no appreciable effect on the 
ant's vitality. 

References: Forbes, 1908, pp. 31-44,. figs. ; Tanquary, 1913, pp. 417-443 ; Severin, 
1920, pp. 1-9 ; Metealf and Flint, 1939, pp. 371-374, 770 ; Talbot, 1945, pp. 504-506 ; 
Talbot, 1946, pp. 65-70 ; Schread and Chapman, 1948, p. 4 ; Talbot, 1953, pp. 3-12 ; 
Wilson, 1955, pp. 97-104 ; Orlob, 1964 (1963) , pp. 95-106. 

Lasius umbratus (Nylander) 

According to Wilson, this species is native to both Eurasia and 
North America. It ranges from Nova Scotia to the Gulf Coast, but is 
rare in the latter region, fairly common in the southern Rocky Moun- 
tains, but sparse or absent over most of western North America ; there 
are no records of it from British Columbia, northern Idaho, or northern 
California. It is the form that has passed in previous American litera- 
ture as a variety or subspecies of umbratus under the name of aphidi- 
cola (Walsh). 

Taxonomic Characters 

Subfamily and generic characters: Same as for alienus except as 
follows : Eye with approximately 12 ommatidia in its greatest diam- 
eter. Antenna 12-segmented, the segments gradually increasing in 
size toward the apex of the funiculus but not forming a distinct club. 
Apex of scape surpassing posterior border of head by less than one- 
third the length of scape. Maxillary palpus with apical segments 
noticeably decreasing in length. Thorax rather short, stout. Declivity 
of epinotum at least twice as long as base of epinotum. Petiolar node in 
profile very narrow or thin, tapering from base to apex. Base of gaster 
scarcely, or not at all, impressed. Specific characters; Workers 3.3- 
3.7 mm. long. Scapes and tibiae normally without erect or suberect 
hairs. Dorsal surface of gaster with numerous, well-distributed, short, 
suberect hairs. Body pubescence short, closely appressed, apparently 




Figure 46.-?- Lasius umbratus (Nylander), lateral view of worker. 



HOUSE-INFESTING ANTS OF THE EASTERN UNITED STATES 85 

denser on dorsal surface of gaster than elsewhere. Body . snm y or 
subopaque depending upon the nature of light and position from 
which viewed. Body color variable, commonly light brown or brown. 
Worker easily recognized by number and relative proportions of seg- 
ments composing maxillary palpus, the very thin or narrow petiolar 
node (in profile) , the usual absence of suberect or erect hairs on scapes 
and tibiae, and the presence of numerous, well-distributed, short, sub- 
erect hairs on the dorsal surface of the gaster. 

Biology and Economic Importance 

This species occurs in varied habitats such as woodlands, meadows, 
swamps, and prairies. It has very diverse nesting habits, nesting in 
the exposed soil, or under the cover of objects, and in and around 
rotting stumps and logs. The exposed nests are often large earthen 
mounds in woodlands and prairies, with grass growing from the 
mounds. In much of eastern North America the ant is regarded as 
a woodland species with a preference for moist nesting sites such as 
under stones or in rotten wood. Van Pelt has found colonies of this 
species common in the Blue Kidge Mountains at 3,500 to 4,000 feet, 
and occasionally at 4,000 to 5,500 feet. Colonies are very populous 
and are thought to contain only a single reproductive female. The 
ants are highly subterranean and light-avoiding, seldom appearing 
above the surface of their nest. Workers forage mostly at night and 
are noted for their love of honeydew, not only tending but fostering 
subterranean plant lice, mealybugs, and coccids on the roots of plants. 
The ants no doubt supplement this food with small insects which they 
kill, and also find dead. No detailed life history studies have been 
made on umbratus in North America; most of our knowledge of the 
species is based on numerous but scattered observations. It appears 
that nuptial flights may take place from July to October, and that 
males and winged females may remain in some of the parental nests 
during the winter. Limited experiments and observations in Europe 
indicate that uwibratus is a temporary parasite in the nests of Lasius 
niger (Linnaeus) and L. alienus. The fertilized female of umbratus 
may be adopted in colonies of niger and alienus by entering a queen- 
less colony of the host, by killing the host queen, or by workers of the 
host species killing their own queen. There may be other methods of 
founding colonies not yet known. In North America we do not know 
how umbratus establishes new colonies, but assume it to be by the same 
methods as in Europe. 

Wheeler stated that he had often found wingless females under 
stones as if in the act of founding colonies independently (but never 
with brood), so he inferred that these females must establish colonies 
by temporary parasitism. Wilson stated that umbratus does not seem 
to form the aerial swarms or clouds that are common to some species 
of Lasius, such as alienus and niger. I have received workers, males 
and winged females, singly or together, from houses from late June 
to October with indications that they were nesting in or around the 
basement walls, like our various species of Acanthomyops. No rec- 
ords have been received of workers infesting household foods, but the 
ants are objectionable to housekeepers, and the winged forms are often, 
mistaken for termites. The ants are of economic importance because 



86 TECHNICAL BULLETIN 1326, U.S. DEFT. OF AGRICULTURE 

of their close relationship with subterranean plant lice, mealybugs, 
and ooccids, and it is highly possible that workers may transmit plant 
diseases by their transportation of these insects. Observers have 
noted catbirds, Dumetelta carolinensis (Linnaeus), and robins, Twrdus 
migratorius Linnaeus, using workers of umbratus in "anting," 

References: Wheeler, 1905b, pp. 373, 397; Wheeler, 1910a, pp. 236-237; 
Wheeler, 1917, pp. 167-176; Donisthorpe, 1927, pp. 264-272; Rau, 1934, pp. 207- 
208 ; Dennis, 1938, pp. 273-274, 296, 306 ; Wheeler and Wheeler, 1944, pp. 257-258 ; 
Wilson, 1955, pp. 162-164 ; Kannowski, 1956, p. 181 ; Kannowski, 1959, pp. 120, 
141 ; Van Pelt, 1963, p. 213. 

Acanthomyops claviger (Roger) 

Smaller yellow ant. A native species, which ranges from Washing- 
ton to Ontario, south to New Mexico and Florida. It is one of the 
most common species of Accmtham/yops, especially in the eastern and 
central United States. 

Taxonomic Characters 

Subfamily and, generic characters: Monomorphic. Antenna 12- 
segmented. Antennal fossa very close to or touching the posterior 
border of the clypeus. Eye very small to small, placed closer to 
posterior border of head than to base of mandible. Maxillary palpus 
short, 3-segmented. Abdominal pedicel composed of a single segment, 
the petiole. Cloacal orifice terminal, circular, surrounded by a fringe 
of hairs (fig. 48, co). Sting lacking. Body not large but stout and 
with a smooth, shiny integument. Body hairs commonly barbed. 
Body color usually a pale yellowish to yellowish red. Workers light- 
avoiding, capable of emitting a pleasant odor similar to lemon verbena 
or citronella. /Specific characters: Bearing superficial resemblance to 
interjectus but distinguished from that species by its smaller size 
(3 4 mm. long) ; absence of pronounced tooth on superior border of 
mandible near junction of masticatory and superior borders (fig. 48, 
b) ; shorter scape, apex of which never surpasses posterior border of 
head; very distinctly clavate funiculus, all segments of which are 
broader than long, except the first and last; and pilosity of dorsum 




Figure 47. AcanMomyops c/aviger ( Roger ), smaller yellow ant, lateral view of worker. 



HOUSE-INFESTING ANTS OF THE EASTERN UNITED STATES 87 

of gaster, whose suberect or erect hairs are usually abundant and well- 
scattered over entire dorsum. Petiolar node in profile similar to that 
of inter jecPus in being very narrow and sharp at summit. 

Biology and Economic Importance 

One of the most common species in the genus, Acanthomyops clavi- 
ger forms populous colonies in the exposed soil, but more often under 
the cover of stones or other objects, and in the rotting wood of logs 
and stumps. The nests are found in such habitats as woodlands (pref- 
erably the open type) , pastures, and grassy fields. Cole found nests 
in Utah at an altitude of 10,000 feet, and Van Pelt has found occa- 
sional colonies in the Blue Ridge Mountains at altitudes between 3,500 
and 5,500 feet. Like other Acanthom/yops, these ants are largely sub- 
terranean and nocturnal. They derive most of their food from honey- 
dew obtained from subterranean plant lice (Prociphilus, Anuraphis, 
and other genera) and mealybugs, which they foster on the roots of 
both wild and domesticated plants. Like all of our Acanthomyops, 
these ants emit a pleasant odor when disturbed; it has been likened 
to that of lemon verbena or citronella. M. S. Blum in lift., wrote 
that the worker emits the pleasant odor from the head, and the dis- 
tinct formic acid odor from the gaster, the latter detectable only when 
the gaster is crushed. Most of the conclusions concerning the biology 
of these ants have been drawn from miscellaneous observations. It 
appears that this species takes its nuptial flights from late August 
into November, especially during the month of September. One ob- 
server noted that during September many square miles of water be- 
tween Welch's Point and Pond Point, Long Island, were covered with 
an average of 35 to 50 winged forms per square foot. There is much 
evidence that males and winged females overwinter in some of the 
nests, either indoors or out, because these forms frequently "swarm 
out" during the winter. These emergences during late December and 
extending into February are not believed to be nuptial flights, but are 
regarded as swarming because of stimulation by favorable temperature 
and moisture. 

No definite information is available on how new colonies are formed. 
Quite often wingless, solitary females are found in the soil beneath 
stones during the winter and early spring. They probably represent 
fertilized females from the nuptial flights of the previous fall. 
Wheeler stated that the female of clamger is capable of establishing 
a colony unaided by workers, but there may be other methods of found- 
ing colonies. Buren intimates that claviger may be a temporary para- 
site in the nest of some other ant, probably Lasius neoniger. A. 
clamger has the same general house-infesting habits as interjectus, 
and a relationship to plant lice and mealybugs similar to that species. 
Workers have been used by starlings, Sturnus vulgaris Linnaeus, and 
males and winged females by blue jays, Cyanocitta cristata (Lin- 
naeus), in "anting." 

References: Wheeler, 1903, pp. 149-163; Wheeler, 1905b, p. 398; Tanquary, 
1911, pp. 294-300; Cole, 1940, pp. 70-72; Cole, 1942, p. 375; Headley, 1943, p. 30; 
Buren, 1944, p. 298 ; Groskin, 1947, pp. 69, 72 ; Van Pelt, 1963, p. 213. 



88 TECHNICAL BULLETIN 1326, U.S. DEPT. OF AGRICULTURE 

Acanthomyops inter jectus (Mayr) 

Larger yellow ant. A native species, interjectus ranges from 

Washington to Ontario and south to New Mexico and Florida. The 

species is more common in the eastern and central United States. This 
ant has occasionally been called the perfumed yellow ant. 

Taxonomic Characters 

Subfamily and generic characters : Same as for claviger. Specific 
characters: Workers 4-4.5 mm. long. Superior border of mandible 
with a small but distinct tooth, which is borne near junction of mastica- 
tory and superior borders of mandible (fig. 48,b) . Apex of scape dis- 
tinctly surpassing posterior border of head. Penultimate segments of 
f uniculus not broader than long. Petiole with a high node which in 
profile is rather narrow and sharp at summit. Dorsum of gaster with 
long, suberect to erect hairs, which are largely confined to first gastric 
segment and to posterior border of each of the succeeding segments, 
where they form distinct transverse rows. 

Biology and Economic Importance 

Unfortunately no complete biological study has been made of inter- 
jecPus, although it is one of our largest and most common species of 
Acanthom/yops. Numerous but scattered observations indicate that 
the ants form rather populous colonies, which nest in the exposed 
soil or under the cover of stones or other objects, and in rotting logs 
and stumps. The nests in exposed soil are usually mounds, frequently 
quite large, especially in Illinois and Wisconsin. The ants commonly 
nest in wooded areas, as well as in pastures, meadows, grassy fields, 
and in or around the foundation walls of houses and other buildings. 
It is believed that males and winged females can overwinter in some 
of the parental nests, and make their nuptial flights the following 
spring, about late March or early April. It is also quite likely that 
winged forms produced during a given season must reach maturity 
by early to late summer, and make nuptial flights shortly thereafter. 




Figure 48. Acanthomyops interjectus (Mayr), larger yellow ant: a. Lateral view of worker; 
fc, left mandible showing small tooth on the superior border near the junction of the masti- 
catory and superior border; co, the terminal orifice, which is surrounded by a fringe of 
hairs. 



HOUSE-INFESTING ANTS OF THE EASTEEN UNITED STATES 89 

At Ardmore, Pa., Groskin observed the ants swarming from a colony 
18 separate times between 6 :30 and 8 :30 p.m., from June 12 to July 
29. On June 12, 13, 15, 23, and 24, five nuptial flights were made. 
He found that mating can take place on the ground in the vicinity of 
the nest. Wheeler stated that the female of interjectus is capable 
of founding her colony independently. The female may also estab- 
lish her colony by becoming a temporary parasite on some other species 
of ant, most probably a common species of Lasius, such as alienus or 
neoniger. To my knowledge, no one has yet found a mixed colony of 
interjectm and another host ant. The ants are largely subterranean 
in habit. Workers do most of the nest building and foraging at night, 
and are seldom seen above the surface of the soil in the daytime, ex- 
cept near their nest, even during swarming and nuptial flights. 

The ants feed almost exclusively on honeydew obtained from sub- 
terranean plant lice and mealybugs. They not only tend these insects, 
but foster them on the roots of wild and domesticated plants. Fre- 
quently, inter jectus nests beneath basement floors, or in and around 
foundation walls of houses and other buildings. The ants may be 
objectionable to housekeepers by throwing out earth from cracks in 
the floor or basement walls, or by giving off numerous winged males 
and females, which are often mistaken for termites. The swarming 
of these ants in houses may occur from late fall to early spring, but 
is especially prevalent from midwinter to early spring. I have no 
records of workers feeding on household foods; nor do I know of any 
significant injury to masonry or woodwork of homes or other build- 
ings. On one occasion, workers were reported to have fallen into an 
open well. The ants are capable of damaging plants by fostering and 
spreading plant lice and mealybugs that feed on plant roots. Some 
of the mealybugs and plant lice may spread viruses or other plant 
diseases, for which the ants may be directly responsible by carrying 
these insects from one plant to another. 

References: Wheeler, 1905b, pp. 373, 397-398; Tanquary, 1911, pp. 294-300; 
Smith, 1928, pp. 14-18 ; Groskin, 1947, pp. 67-72 ; Smith, 1950, pp. 293-294. 

Acanthomyops murphyi (Forel) 

This native species ranges from Montana to Ontario and south to 
Colorado and Georgia. According to Wheeler (1917, a), "this form 
appears to belong to the dryer and warmer portions of the transition 
zone, and to be rare in all parts of its range." 

Taxonomic Characters 

Subfamily and generic characters: Same as for claviger. Specific 
characters: Workers 3-3.7 mm. long. Distinguished by small size, 
small eye, which contains approximately 8 ommatidia in its greatest 
diameter and measures 0.10 mm. here; short scape, apex of which 
scarcely attains or barely surpasses posterior border of head ; slender 
but subclavate f uniculus, all segments of which appear to be as long 
as broad or longer than broad ; thick petiolar node with blunt summit 
(in profile) ; and unusually short body hairs, which are especially 
abundant and noticeable on epinotum and petiole. 



90 TECHNICAL BULLETIN 1326, U.S. DEPT. OF AGRICULTURE 




Figure 49. Acanthomyops murphyi (Forel), lateral view of worker. 

Biology and Economic Importance 

.Less is known about murphyi than any other species of Aeantho- 
myops discussed in this paper. Since the ant is only infrequently col- 
lected, there are almost no published notes on its biology. Although 
rather widely distributed, the species seems to be uncommon through- 
out its range. The ants usually nest in populous colonies in the soil 
beneath stones and other objects, more frequently in the open woods 
in our Eastern States. Creighton remarks that in the West, their nests 
often occur in cottonwood groves near stream bottoms. It is quite 
likely they may also nest in rotting stumps and logs. The workers 
undoubtedly obtain most of their food from honeydew of subterranean 
plant lice and mealybugs on the roots of plants. Vickery records them 
tending the corn root aphid Anuraphis maidiradicis (Forbes), an im- 
portant pest of corn, cotton, and other crops. 

Fragmentary records indicate that males and winged females are 
probably produced from approximately June 15 to midsummer or late 
summer, and that nuptial nights take place thereafter, perhaps ex- 
tending into the fall. Forel witnessed a nuptial flight in North Caro- 
lina on July 16 following a rain; at the same time he also observed 
isolated wingless (presumably fecund) females running around on 
the ground. It appears from these and other observations that the 
ants can make their nuptial flights during the day, at dusk, or in the 
early night, and that they can mate in or on the soil without the neces- 
sity of a flight. As with inter jectus, males and winged females also 
overwinter in the parental nest and make their nuptial flights the fol- 
lowing year, perhaps in the spring. It is likely that new colonies are 
formed by the fertilized queen becoming a temporary parasite in the 
nest of another species of ant, most probably one or more of the com- 
mon forms of Lasius. The peculiar aberrant, highly pilose female of 
murphyi suggests that this species is probably a temporary parasite. 
. Dr. Mary Talbot (in press) has the following to say : "Young colo- 
nies of Aoanthomyops are extremely difficult to find because they are 
hypogaeic at all times except when the mature colonies come to the 
surface for flights. It has been assumed that Acanthomyops females 
become temporary social parasites when beginning a colony. One bit 



HOUSE-INFESTING ANTS OF THE EASTEKN UNITED STATES 91 

of evidence was found to substantiate this. On August 22, 1961 a small 
mixed colony of A. murphyi and Lasius neoniger containing A. 
murphyi worker pupae was found under a stone set firmly into a hill- 
side. Part of the mixed colony was kept alive in the laboratory for 
several days. Whenever the container was opened, workers of Lasius 
and Acanthomyops cooperated in carrying pupae out of the light. A 
week after I made the collection, the mixed colony was still there. 
Aside from this, I have seen no evidence of colony founding in my 
ten years at the reserve." 

A. rrwrphyi has the same general house-infesting habits as inter- 
jectus, but apparently is much less common in this respect than inter- 
jectus and claviger. Our unquestionable records show that murphyi 
has been collected in houses mostly during June, July, and August. 
An observer noted that the purple grackle, Quiscalus guiscala (Lin- 
naeus), used workers and winged females of this species in "anting." 

References: Forel, 1901, p. 369; Wheeler, 1905b, p. 398; Vickery, 1910, p. 105; 
Wheeler, 1917a, p. 530 ; Oreighton, 1950, p. 432. 

Acanthomyops latipes (Walsh) 

This native species ranges from Alaska and Quebec south to New 
Mexico and South Carolina. It is widely but apparently sporadically 
distributed, and is most common in the eastern and central Unitea 
States, although less common in the Eastern States than claviger and 
inter yectus. Creighton (1950) states that the species is not common 
south of the latitude of Pennsylvania. 

Taxonomic Characters 

Subfamily and generic characters: Same as for claviger. Specific 
characters: Workers 3.5-3.75 mm. long. Head subrectangular, longer 
than broad, with slightly emarginate posterior border. Scape rather 
short, when fully extended its apex either scarcely attaining or barely 
surpassing posterior border by less than greatest width of scape. 
Funiculus noticeably enlarged through segments 6-11, only the first 




Figure SO.Acanfhomyops lafipes (Walsh), lateral view of worker. 



92 TECHNICAL BULLETIN 1326, U..S. DEPT. OF AGRICULTURE 

and last segments of funiculus distinctly longer than broad. Eye 
.small, approximately 0.13 mm. in its greatest diameter, usually with 
8 or 9 ommatidia in this diameter. Petiolar node in profile thick and 
with blunt, nontapering summit. Body hairs rather abundant, erect 
or suberect, slender and long, apparently longest on gaster. Hairs 
present on cheeks, gula, and petiolar node. Distinguished especially 
by the thick petiolar node with blunt summit and the long, sub- 
erect or erect body hairs. There seems to be considerable variation in 
latipes. Specimens I consider typical have heads distinctly longer 
than broad with subparallel sides and emarginate posterior border. 

Biology and Economic Importance 

A. latipes is one of the less common species of Acanthomyops treated 
in this paper. The ants usually nest in open woodlands, grassy fields, 
meadows, and pastures in rather dry to moist soils. Nests may be 
constructed in the exposed soil, under stones or other objects, or at the 
base of stumps. Weber believes that its habit of nesting under large 
rocks affords it, as well as other ants, protection during severe drouth 
periods such as occurred in South Dakota in the thirties. Quite often 
soil nests are in the form of earthen mounds a foot or more in diameter 
and several inches high, with gra'ss growing from them ; they contain a 
large number of entrance and exitjioles. Workers are largely subter- 
ranean and nocturnal and feed almost exclusively on honeydew which 
they obtain from subterranean plant lice and mealybugs on the roots of 
wild and domesticated plants. No detailed biological studies of latipes 
have been made, but numerous and scattered observations appear to 
indicate that males and winged females are produced in early to mid 
summer, and that these adult forms, common in nests during July and 
August, take their nuptial flights in August and September, but it is 
believed that some of the males and winged females can overwinter in 
parental nests and make nuptial flights the following year. The species 
is unique in possessing two forms of females, an alpha and a beta. The 
beta form, which is the more common of the two, but also the more 
aberrant, is yellowish red, heavily pilose, with short, thick antennae 
and extraordinarily broadened and flattened femora and tibiae. The 
alpha form is darker and somewhat intermediate in structure between 
claviger and the beta form. One of the theories explaining the dimor- 
phism of the females is that it may be a hybridism between claviger 
and latipes. To support this theory Wheeler mentions the occurrence 
of nests of the two species within 20 feet of each other producing 
nuptial flights at the same time (Sept. 17, 1902) . 

Limited data suggest that the female of latipes probably founds her 
colony by becoming a temporary parasite on some other species of ant, 
most probably a Lasius. To support this belief, Wheeler found mixed 
colonies of latipes and L. alienus (= americanus) in the field on five 
occasions. Tanquary, in a large series of experiments with latipes and 
eight species of Lasius and Acanthomyops, induced latipes to obtain 
adoption in one colony of alienus and one colony of A . inter jectus. One 
of the requisites of a parasitic species is that it produce an abundance 
of females ; this is true of latipes. Another is that the parasitic species 
seek one or more common, widespread hosts. The two forms of Lasius 
in the. eastern United States most accessible and satisfactory as hosts 



HOUSE -INFESTING ANTS OF THE EASTERN UNITED STATES 93 

for latipes would probably be L. neoniger and alienus. The house-in- 
festing habits of latipes are generally similar to those of inter jectus. It 
would appear that the species is a much less common house pest than 
claviger and inter jectus. I have received latipes for identification on 
only two occasions, both from South Carolina, once from a drugstore 
where winged females were emerging on June 30, and once from a 
house where females were collected on July 24. 

References: Wheeler and McClendon, 1903, pp. 149-163; Wheeler, 1905b, p. 
398; Tanquary, 1911, pp. 294-300; Cole, 1942, p. 375; Weber, 1942, pp. 61-62; 
Buren, 1944, p. 298 ; Cole, 1954, p. 284 ; Kannowski, 1956, p. 181. 

GLOSSARY 

Abdominal pedicel. The one or two basal segments of the abdomen between 

the epinotum and gaster. 
Anal glands. Glands near the anus of worker ants of the subfamily Dolicho- 

derinae, which produce a sticky secretion with a disagreeable odor ; the secre- 
tion is often ejected on other ants as a means of offense or defense. 
Angulate. Having angles. 
Antenna. The segmented, flexible appendage articulated to the head on the 

external side of the frontal carina and posterior to the clypeus ; it is an organ 

of sensation, such as touch and smell. 
Antennal club. The very much enlarged or clublike distal segments of the 

funiculua ; may be composed of two or more segments, commonly two- or 

three-segmented. 
Antennal fossa. The concavity or socket in the head in which the base of the 

antenna is articulated. 
Antennal insertion. Literally, the place where the base of each antenna is 

articulated to the head ( see antennal fossa ) . 
Antennal scape. The greatly elongated first segment of the antenna ; the scape 

lies between, the articulation of the antenna to the head and the fuuiculus 

(fig. 1). 
Anterior border of clypeus. The anterior margin of the clypeus above the 

mandibles and between the cheeks. 
Anterior border of mesonotum. The border of the mesonotum directly posterior 

to (behind) the pronotum, and commonly separated from the pronotum by the 

promesonotal suture. 
Anterior border of mesopleuron. The front border of the side of the meso- 

thorax ; this commonly lies somewhat above and behind the front coxa ; the 

ant Solenopsis geminata normally has an irregular border of toothlike or 

spined projections. 
Antero-ventral tooth of petiole. An irregular or toothlike protuberance on the 

ventral surface of the petiole, usually somewhat in front of the petiolar node 

(fig. 20). 
Anting. A term applied by ornithologists to a habit of many birds of allowing 

ants to crawl on them, or of placing ants on their bodies. One possible 

explanation is that the ants remove vermin from the bird's body by ejecting 

formic acid. Another is that the formic acid emitted by the ants may stimulate 

the birds themselves. 
Apical teeth. The larger or more distinct teeth borne on the masticatory border 

of the mandible near and also at its junction with the lower or inferior 

border. 

Appendages. The antennae, mandibles, and legs. 
Appressed. Lying close to or against; the term usually applies to the position 

occupied by hairs or pubescence in respect to the body surface. 
Arboreal. Nesting or foraging in trees. 
Armed. Bearing a pair of spines, or toothlike projections. 

Barbed hairs. Hairs bearing bristlelike lateral hairs ; such hairs are char- 
acteristic of ants of the genus Acanthomyops and are best seen under high 

magnification. 



94 TECHNICAL BULLETIN 1326, U..S. DEPT. OF AGRICULTURE 

Basal teeth of mandible. In the broad sense, the teeth on the masticatory 
border of the mandible, exclusive of the apical teeth ; in ants of the genus 
Lasius, the term applies to the three dorsal-most teeth. 

Base of mandible. The point where the mandible is articulated to the head. 

Base of epinotum. The dorsal surface of the epinotum lying between the meso- 
epiriotal suture and the declivity of the epinotum. 

Bicarinate. With two ridges or keels; such structures are common on the 
clypeus of ants of the genera Solenopsis and Monomorium. 

Bilobed. With two lobes ; the term applies especially to the soldier of species 
of the genus Pheidole, the head of which is divided into two prominent, oc- 
cipital lobes posteriorly. 

Body hairs. The longer, and usually coarser, suberect to erect hairs of the body 
and appendages; normally slender and flexible, the hairs at times may be 
very coarse or bristlelike. 

Bristles. Coarse, stiff hairs ; the term is applied commonly to the row of grad- 
uated bristles on the flexor surface of the middle and hind tibia. 

Carina (pi., carinae). An elevated ridge or keel of varying height and sharp- 
ness (fig. 1) . 

Carnivorous. Flesh-eating. 

Castaneous. Bright red brown or chestnut brown. 

Caste. A term applied to various nature forms of ants, such as worker, female, 
male, soldier, et cetera. 

Cheek. The area on the side of the head between the eye and the base of the 
mandible. 

Cloacal orifice terminal, circular, surrounded by a fringe of hairs. The cone- 
shaped structure with a circular opening surrounded by a fringe of hairs at 
the apex of the gaster (fig. 48,co) ; the structure is characteristic of ants of 
the subfamily Formicinae. It is not always easily identifiable because the 
apical segments of the gaster may be retracted, or the fringe of hairs worn 
away. 

Cloacal orifice transverse, ventral, slit-shaped, without a fringe of hairs. This 
structure can be observed when the ventral surface of the gaster is exposed ; 
it is then seen as a transverse slit without a fringe of hairs, which is located 
in front of the apex of the gaster (fig. 31,co) . Characteristic of the subfamily 
Dolichoderinae. 

Compound nest. A nest composed of several similar and interrelated nests. 

Compressed. The appearance of having been pressed in at the sides. 

Conulate. Somewhat cone-shaped. 

Clypeus. That portion of the head bounded anteriorly (below) by the labrum, 
posteriorly (above) by the frons, and laterally by the cheeks (fig. 1). 

Clypeal fossa. A rather deep concavity or pitlike impression on the side of the 
clypeus ; especially characteristic of the major workers of Camponotus penn- 
sylvanious. 

Clypeus with a median longitudinal carina. That is, with a longitudinal ridge 
extending through the median plane of the clypeus (fig. 1). 

Dealate. Wingless; a term applied to formerly winged females or queen ants 
that have shed their wings. 

Declivity of epinotum. The posterior surface of the epinotum ; the area is in 
front of the petiolar node, and is usually inclined. 

Declivous surface of the epinotum. Same as declivity of epinotum. 

Denticulae. Extremely small, often not clearly discernible, teeth on the masti- 
catory border of the mandible ; the same border may contain both teeth and 
denticulae. 

Dimorphic. Literally two forms ; the term applies to worker ants having two 
distinct sizes and shapes, a large major worker or soldier and a smaller, nor- 
mal worker. The genus Pheidole is noted for its dimorphic workers. 

Dorsally. Pertaining to the upper surface. 

Dorsal surface. The upper surface. 

Dorsum. The upper surface. 

Ecarinate. Without a carina or ridge. 

Emarginate. Notched. 

Emargination. A notch. 

Epinotal spine. A nonarticulate spine or toothlike projection borne on the 
epinotum near where the base and declivity meet; especially characteristic 
in ants of the subfamily Myrmicinae. 



HOUSE -INFESTING ANTS OF THE EASTERN UNITED STATES 95 

Bpinotum. That part of the. thorax behind the mesoepinotal suture; in worker 
ants the term is loosely applied, since the region morphologically is composed 
of two segments, an anterior metathorax and a posterior epinotum (fig. 1). 

Erect. Standing out ; the term usually applies to the position of the larger 
hairs that are nearly vertical to the body surface. 

Excised. With a deep cut or notch. See emargination. 

Extrafloral nectaries. . Plant structures not associated with flowers that produce 
a sweet secretion or nectar relished by ants as food. 

Eye. The eye, or compound eye, is one of the paired organs of sight ; it is com- 
posed of a highly variable number of units called ommatidia ; the size of the 
eye, and the position it occupies on the side of the head vary greatly (fig. 1). 
See also ocellus. 

Facet. The external surface of an ommatidium ; one of the seeing units compos- 
ing the compound eye. 

Farinaceous. Made of meal or flour ; mealy. 

Femur (pi., femora). The large . thighlike segment of the leg between the 
trochanter and tibia (fig. 1) . 

Ferrugineous. Rusty red-brown. 

Flange. A projecting rim or edge ( flg. 5,b ) . 

Flexor surface. With reference to the leg, the posterior or hind edge of the 
tibia. 

Floral nectaries. Certain parts of flowers that secrete a sweet liquid or nectar 
relished by ants for food. 

Fore tibia. Tibia of the anterior or front leg. 

Foster. The term applied to the intimate relationship of ants with honeydew- 
excreting insects in which the ants gather, distribute, or care for these insects. 
The ants benefit from the association by obtaining honey dew for food and the 
honeydew-excreting insects benefit by receiving care and protection. 

Foveolate. With a deep depression. 

Frontal area. The small triangular area lying between the frontal carinae and 
posterior to (above) the clypeus (fig. 1). 

Frontal carina. The longitudinal ridge, on the inner side of the insertion of the 
.antenna (fig. 1). 

Frontal furrow. The longitudinal impression or groove extending from the 
frontal area toward the median or anterior ocellus (flg. 1) . 

Frontal lobe. The platelike extension of the frontal carina above the insertion 
of the antenna. 

Funiculus. All of the antenna excluding the scape ( flg. 1 ) . 

Gaster. That portion of the abdomen behind the petiole in ants with a single- 
segmented petiole, and behind the postpetiole in ants with a two-segmented 
petiole (flg. 1.). 

Gibbosity. A protruding area. 

Graduated bristles. Bristles arranged in a row at equidistant, well-spaced inter- 
vals ; see bristles and figure 38. 

Granivorous. Feeding on grain or seeds. 

Habitat. The natural abode of an animal or plant. 

Hair. The longer and usually coarser pile of the body and appendages in con- 
trast to pubescence ; especially on the body, the hairs are usually more erect 
or suberect. 

Hind tibia. The slender, usually long segment of the hind leg between the femur 
and first tarsal segment (flg. 1 ) . 

Honeydew. A sweetish alimentary excretion produced by certain insects such as 
plant lice, mealybugs, and scales, and greatly relished as food by ants. 

Humeral angles. The anterolateral corners of the prothorax. 

Hypogaeic. Subterranean. 

Incurved. With a strong convexity externally and a strong concavity inwardly ; 
typical in mandibles of Solenopsis geminata ( F. ) . 

Infuscation. A smoky gray-brown or blackish tinge. 

Integument. The outer covering, or cuticle, of the insect's body. 

Lamella. A thin plate or leaflike process. 

Lyrate. Lyre-shaped. 

Male. In ants, the male functions only for the purpose of mating and dies shortly 
after this takes place ; it is smaller than the female and possesses wings. It is 
characterized by a small head, large eyes, and prominent genital appendages. 

749-306 O 65 7 



96 TECHNICAL BULLETIN 1326, U.S. DEPT. OF AGRICULTURE 

Mandible. One of the pair of biting jaws lying below or anterior to the clypeus, 

the masticatory border of which bears teeth (flg. 1) . 
Mandible strongly incurved. With a strong convexity externally and a strong 

concavity Inwardly ; typical in mandibles of Solenopsia geminata (F. ) . 
Masticatory border of mandible. The chewing border of the mandible ; that bor- 
der which bears the teeth (flg. 20,b) . 
Maxillary palpus. One of the paired, segmented, feelerlike structures beneath 

the front portion of the head, anterior and lateral to the labial palpus (flg. 

42) ; it is normally longer than the labial palpus. 
Mesoepinotal impression. A pronounced transverse furrow or groove at, or in 

the vicinity of, the mesoepinotaT suture. 

Mesoepinotal suture. The suture separating the mesonotum from the epinotum. 
Mesonotum. The dorsal surface of the mesothorax. 
Mesopleuron. The side of the mesothorax ; in general, that area above the coxa 

of the second leg. 
Mesothorax. The second segment of the thorax ; the segment bearing the second 

pair of legs (flg. 1). 
Metapleuron. The side of the metathorax ; in general, the area above the coxa 

of the third leg. 
Metasternal spine. A spine borne at or near the posterolateral angle of the 

thorax ; typical of Tetramorium guvneeme (F.) (flg. 25). 
Middle tibia. That segment between the femur and first tarsal segment of the 

second or middle leg. 
Monomorphic. Of one form; descriptive of those worker ants which are not 

appreciably different in size or form, as Monomoriwm pharaonis (L.). 
Nuptial flights. The mating flight of female and male ants. It should be under- 
stood that all ants do not need to take flight and mate in the air ; some mate 

inside of the nest, others on the soil, plants, or other objects outside of the 

nest. 

Obsolescent. In the process of disappearing or of becoming useless. 
Ocellus (pi., ocelli). A small, single-lens eye located on the vertex of the head, 

usually 3 in a triangle (flg. 1) ; ocelli are not present on worker ants of all 

species. 

Occipital border. The hind margin of the head. 

Occipital lobes. The prominent, posterolateral corners of the head, characteris- 
tic of the major workers (soldiers) of species of Pheidole. 
Occiput. That portion of the head between the vertex and neck (flg. 1). 
Ommatidium (pi., ommatidia). One of the visual units comprising a compound 

eye. 

Omnivorous. Eats everything. 
Opaque. Not shiny ; without luster ; nontransparent. 
Pedicel. The one or two basal segments of the abdomen between the epinotum 

and gaster. 

Pedunculate. Set on a stalk. 
Penultimate tooth of mandible. Next to the last tooth of the mandible ; the last 

tooth is the one on the masticatory border nearest the superior border. 
Petiolar node. The greatly enlarged portion of the petiole. The node may be 

of diverse sizes and shapes. 
Petiolar node scalelike, In profile. The node is narrow and upright or inclined 

(figs. 30 and 43). 

Petiole. A pedicel composed of only one segment, or the first segment of a two- 
segmented pedicel (fig. 1). 

Piceous. Pitchy dark brown ; between fuscous and black. 
Piligerous foveolae. Coarse, pitlike depressions that bear erect hairs; present 

on the cheeks of Camponotus caryae discolor (Buckley) (flg. 38, a) . 
Pilosity. Hairiness, in contrast to pubescence, which is usually shorter, finer, 

and more appressed. 
Posterior border of clypeus. The transverse suture at the rear of the clypeus 

which lies in front of the antennal insertions, the frontal carinae, and the 

frontal area (flg. 1). 
Postpetiolar node. The greatly enlarged portion of the postpetiole. The node 

may be of diverse sizes and shapes. 
Postpetiole. The second or posterior segment of a two-segmented pedicel. 



HOUSE -INFESTING ANTS OF THE EASTERN UNITED STATES 97 

Polymorphic. Many forms. The term refers to those species of ants having 
minor, intermediate, and major workers; ants of the genus Camponotus are 
excellent examples. 

Predacious. Living by preying on other animals. 

Promesonotal suture. The suture separating the pronotum from the mesonotum ; 
it may be well developed or more or less obsolescent. 

Promesonotum. The combined pronotum and mesonotum. 

Pronotum. The dorsal surface of the prothorax. 

Prothorax. The first segment of the thorax ; the segment bearing the first pair 
of legs (fig. 1). 

Pruinose. Giving the effect of a frosted covering, or "bloom" ; characteristic 
of IritLomyrmex pruinosws. 

Psammophore. Beard ; referring to the long hairs beneath the head which are 
arranged in a comblike series (fig. 30). 

Pubescence. Short, fine, often strongly appressed hairs covering the body and 
appendages. See also pilosity. 

Punctulate. Covered with fine, almost obsolete punctures. 

Queen (female). The. individual that normally carries on reproduction; she is 
usually larger than the worker or male, and before mating, normally possesses 
two pairs of wings ; in most colonies the queen, after establishing her nest and 
rearing her first brood alone, functions only as an egg producer, with the care 
and feeding of the brood relegated to the workers. 

Reticulate-rugose. Consisting of netlike sculpturing intermixed with irregular 
and rough wrinkles. 

Rugose. Irregularly and roughly wrinkled. 

Rugulose. Irregularly but not roughly wrinkled. 

Rugulose-reticulate. Irregularly but not roughly wrinkled combined with net- 
like sculpturing. 

Scape. The greatly elongated first segment of the antenna ; it lies between the 
funiculus and the articulation of the antenna to the head (fig. 1). 

Scrobe. A groove for the reception of the appendage; as the antennal scrobe 
for the reception of the scape (fig. 25). 

Spine. A nonarticulated thornlike outgrowth of the body wall; especially ap- 
plicable to the paired projections on the epinotum of ants, especially those of 
the subfamily Myrmicinae. See epinotal spine. 

Spiracle. An external opening of the respiratory system. 

Sting. The modified ovipositor; a needlelike organ near the apex of the gaster 
used as an organ of offense or defense ; absent or vestigial in some subfamilies 
of ants such as the Dolichoderinae and Formicinae. Since the sting is capable 
of retraction, it can not always be seen on a worker or female ant. 

Striate. Marked with fine, more or less parallel, impressed lines. 

Subcarinate. Scarcely carinate ; that is, without a very distinct ridge or keel ; 
the term is commonly used to describe the nature of the single, longitudinal 
carina of the clypeus. 

Subcordate. Approximately heart-shaped ; the term is applied to the shape of 
the gaster of ants of the genus Crematogaster and is best seen from above. 

Subereet hairs. Hairs borne at a distinct angle to the surface of the body or its 
appendages, neither appressed nor vertical (q.v.) . 

Subopaque. Nearly opaque. 

Sulcate. Grooved or furrowed. 

Sulcus. A groove or furrow. 

Superior border of mandible. The dorsal border of the mandible; that border 
nearest the anterior border of the clypeus. 

Suture. A seam or impressed line indicating the divisions of the parts of the 
body wall. 

Tarsal claw. One of the pair of claws borne on the apical tarsal segment of the 
leg. 

Teeth. Strictly speaking, the irregularly shaped structures on the masticatory 
border of the mandible used for biting or chewing ; broadly speaking, any pro- 
jections of the body wall that are toothlike in form. 

Temporary host. The species of ant whose colony is invaded temporarily by a 
queen of an alien species. See temporary parasite. 

Temporary parasite. The female of certain ants who seeks adoption in a colony 
of an alien species. To accept such a queen the alien colony must be queen- 
less, the queen is killed by her own workers, or by the invading queen ; after 



98 TECHNICAL BULLETIN 1326, U.S. DEPT. OF AGRICULTURE 

the death of the host workers, the colony eventually becomes purely one of 
the same species as the invading queen. 

Tend. Applied to the visits of ants on insects for the purpose of obtaining 
honeydew for food. 

Terminal basal tooth. The most-dorsal tooth on the masticatory border of the 
mandible ; the tooth nearest the clypeus. 

Tibia. The fourth division of the leg ; the slender segment between the femur and 
first tarsal segment (flg. 1) . 

Trapezoidal. In the form of a four-sided figure, two sides of which are parallel 
and two are not. 

Unarmed. That is, without a pair of spines or toothlike projections. 

Ventral. The lower surface ; opposite the back, or upper surface. 

Vertex. That portion of the head lying between the front and occiput and mid- 
way between the sides of the head (fig. 1) . 

Vestigial. Small or degenerate ; in the process of disappearing. 

Viable. Capable of living. 

Virgin female (virgin queen). The unmated individual, or the one that still 
bears two pairs of wings ; it is assumed that this individual never sheds her 
wings until she has mated ; see also definition of queen (female). 

Worker. Usually an undeveloped female, differing from the queen in its smaller 
size, lack of wings, and other morphological features ; the normal functions of 
the worker are foraging for food, care of the brood and nest, and defense of 
the colony. 

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1954. THE IMPORTED FIEB ANT, HOW TO CONTROL IT. U.S. Dept..AgT. Leaflet 

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1957. SKIN RESPONSES TO THE STING OF THE IMPORTED FIBE ANT (SOLENOPSIS 

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1940. NEW INTERMEDIATE HOSTS OF FOWL CESTODES. Kans, Acad. Sci. Trans. 

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HOUSE-INFESTING ANTS OF THE EASTEKN UNITED STATES 99 
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1940. A GUIDE TO THE ANTS OF THE OKEAT SMOKY MOUNTAINS NATIONAL PABK, 

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1942. THE ANTS or UTAH. Amer. Midland Nat. 28 : 358-388. 

1954. STUDIES ON NEW MEXICO ANTS. XIII, THE GENERA ACANTHOMYOPS, MYRME- 

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1930. THE NEW WORLD SPECIES OF THE GENUS soLENOpsis. Amer. Acad. Arts 
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1950. THE ANTS. OF NORTH AMERICA. Harvard Univ., Mus. Compar. Zool. 
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1908, NESTS OF THE CARPENTER ANT. Staten Isl. [N.Y.] Inst. Arts and Sci. 

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1922. AN ANNOTATED LIST OF THE ANTS OF STATEN ISLAND AND LONG ISLAND, N.Y. 

Brooklyn Ent Soc. Bui. 17 : 1-25. 
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1938. THE DISTRIBUTION OF ANT SPECIES IN TENNESSEE WITH REFERENCE TO 

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1927. BRITISH ANTS, THEIR LIFE-HISTORY AND CLASSIFICATION. 2nd. Cd. GCO. 

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1940. FIRE -ANTS CAUSING DAMAGE TO TELEPHONE EQUIPMENT. Jour. EcOIl. 

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ECKEBT, J. E., AND MALLIS, A. 

1937. ANTS AND THEIR CONTROL IN CALIFORNIA. Calif. AgT. EXpt Sta. Cir. 

342: 37 pp., figs. 

ElDMANN, H. 

1944. DIE AMEISEWFAUNA VON FERNANDO poo. Zool. Jahrb., Abt. f. System. 
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ENZMANN, B. V. 

1951. A LEAD DESTROYING ANT FROM PANAMA. Iowa Acad. Sci. Proc. 58: 449- 
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1926. INSECTS OF WESTERN NORTH AMERICA. The Macmillan Co., N.Y., 1035 

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1958. THE IMPORTED FiBE ANT. U. 'S. Pub. Health Serv., Pub. Health Rpts. 

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1947. THE LITTLE FIRE! ANT AS A HOUSE PEST. Jour. Econ. Ent. 40 : 428. 

FIELDS, A. M. 

1904. OBSERVATIONS ON ANTS IN THEIR RELATION TO TEMPERATURE AND TO SUB- 

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1908. HABITS AND BEHAVIOB OF THE CORN-FIELD ANT, LA8IUS NIGER AMERICANUB. 

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1901. VARIETIES MYRMfiCOLOGIQUES. A - .FORMES NEOTBOPIQUES ET NEARCTI- 

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1961. ANTS ATTACKING FLEAS IN PUERTO RICO. Jour. Econ. Ent 54: 1065- 

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1942. THE BLACK CARPENTER ANT. PestS 10 I 12, 14. 

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1937. THE CONTROL OF CARPENTER ANTS IN TELEPHONE POLES. , COBU, Agr. Expt. 

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1914. RESULTS OF THE MEBSHON EXPEDITION TO THE CHARITY ISLANDS, LAKE 

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100 TECHNICAL BULLETIN 1326, U.S. DEPT. OF AGRICULTURE 
GBAHAM, S. A. 

1918. THE CARPENTER ANT AS A DESTROYER OF SOUND WOOD. Minn. State Ent. 

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1944. THE AN.TS OF THE CHICAGO REGION. Ent. Soc. Amer. Ann. 37 : 447-480. 

1946. THE ANTS OF NORTHEASTERN MINNESOTA. Amer. Midland Nat. 36 : 747- 
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GREEN, H. B. 

1952. BIOLOGY AND CONTROL OF THE IMPORTED FIRE ANT IN MISSISSIPPI. JOUr. 

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1942. ANTS AS PROBABLE AGENTS IN THE SPREAD OF SHIGELLA INFECTIONS. 

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1947. NOCTURNAL ACTIVITIES AND NOTES OF THE ANT LASIUS (ACANTHOMYOPS) 

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1920. SOLENOPSIS MOLESTA SAY : A BIOLOGICAL STUDY. Kans. Agr. Expt. Sta. 

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1943. THE ANTS OF ASHTABULA COUNTY, OHIO. Ohio JOUT. Sci. 43 : 22-31. 

1949. A POPULATION STUDY OF THE ANT, APHAENOGASTER FULVA 8UBSP. AQUIA 

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1930. OBSERVATIONS ON THE NESTS OF APHAENOGASTER FULVA BUBSP. AQUIA 

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1914. INSECTS INJURIOUS TO THE HOUSEHOLD AND ANNOYING TO MAN. The 

Macmlllan Co., N. Y., 470 pp. 
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1958. THE ANTS OF DALLAS COUNTY, TEXAS, AND THEIR NESTING SITES ; WITH 
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1938. OBSERVATIONS ON THE LIFE HISTORY OF EAIIZJETINA ECHINOBOTHRIDA AND 

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1912. TWO DESTRUCTIVE TEXAS ANTS. U. S. Dept. Agr., Bur. Ent. Cir. 4, 

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1957. THE IMPORTED FIRE ANT, SOLENOPSIS SAEVIS8IMA RICHTERI AS AN AGENT 

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KALSHOVEN, L. G. E. 

1937. VERDERE AANTEEKENINGEN OVER DE HUISMIER, MONOMORIUM DESTRUCTOR 

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1956. THE ANTS OF RAMSEY COUNTY, NORTH DAKOTA. Amer. Midland Nat. 56 : 
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1959. THE FLIGHT ACTIVITIES AND COLONY FOUNDING BEHAVIOR OF BOG ANTS IN 

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1960. AMEISEN ALB SCHAFDLINGE VON POLYAETHYLEN-UMMANTELTEN KABELN. 

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1948. A TROPICAL ANT TEMPORARILY ESTABLISHED IN IOWA. lOWE Acad. Sci. 

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1961. PAVEMENT ANT ATTACKING SUGAR BEETS IN CALIFORNIA . JOUr. EcOU. Ent. 

54 : 1063-1064, fig. 
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1942. ANTS AS PREDATORS OF COCHLIOMYIA AMERICANA C. AND P. JOUr. EcOn. 

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LYLE, C., AND FORTUNE, I. 

1948. NOTES ON AN IMPORTED FIRE ANT. Jour. Econ. Ent. 41 : 833-834. 



HOUSE-INFESTING ANTS OF THE EASTERN UNITED STATES 101 
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1945. A NOTE ON THE SW ARMING OP SOLENOPSIS MOLESTA SAY. Canad Ent 

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1938. THE OALIFOBNIA PIKE ANT AND ITS CONTROL. Pan-PaClflC Ent. 14 I 87-91. 
1941. A LIST OF THE ANTS OP CALIFOENIA WITH NOTES ON THEIE HABITS AND 

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MALLOCH, J. E. 

1912. THE INSECTS OP THE DIPTEROUS FAMILY PHORIDAE IN THE UNITED STATES 

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1898. HOUSE ANTS. U.S. Dept. Agr. Cir. 34, 2d series, 4 pp., flgs. 

1916. HOUSE ANTS : KINDS AND METHODS OF CONTROL. U.S. Dept. Agr Farmers' 

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1916. A PRELIMINARY REPORT ON THE LIFE ECONOMY OF SOLENOPSIS MOLESTA 

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1876. NOTES ON THE ARCHITECTURE AND HABITS OF FORMICA PENNSYLVANIA, 

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1879. CUTTING OR PARASOL ANT, ATTA FERVEN8 SAY. Acad. Nat. Sci. Phila. 
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1883. HOW A CARPENTER ANT QUEEN FOUNDS A FORMICARY. Acad. Nat Sci 

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1939. DESTRUCTIVE AND USEFUL INSECTS. 2d. ed. McGraw-Hill Book Co. Inc., 
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MITCHELL, J. D., AND PIERCE, W. D. 

1912. THE ANTS OF VICTORIA COUNTY, TEXAS. Ent. Soc. Wash. Proc. 14: 
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NEWELL, W. 

1908. NOTES ON THE HABITS OF THE ARGENTINE OR "NEW ORLEANS" ANT, IRI- 

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1909. THE LIFE HISTORY OF THE ARGENTINE ANT. Jour. Econ. Ent. 2: 174- 

192, figs. 
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1913. THE ARGENTINE ANT. U.S. Dept. Agr., Bur. Ent. Bui. 122, 98 pp., figs. 

1914. A NATURAL ENEMY OF THE ARGENTINE ANT. Jour. ECOU. Ent. 7: 147. 

ORLOB, G. B. 

1964. THE HOLE OF ANTS IN THE EPIDEMIOLOGY OF BARLEY YELLOW DWARF VIRUS 

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1956. THE MEDICAL AND VETERINARY IMPORTANCE OF THE FORMICIDAE. InSCCteS 

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1948. COMPARISON OF DDT, CHLORDANE AND CHLORINATED CAMPHENE FOR CON- 
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PEACOCK, A. D., AND BAXTER, A. T. 

1950. STUDIES IN PHARAOH'S ANT, MONOMOBIUM PHAHAONIS (L.) 3. LIFE HIS- 
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1950. THE BIOLOGY AND CONTROL OF THE ANT PEST MONOMORIUM PHARAONIS .(L.) 

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1934. THE BIOLOGY AND DISTRIBUTION OF ANTS IN HAWAIIAN PINEAPPLE FIELDS. 

Hawaii Univ. Expt. Sta., Pineapple Prod. Coop. Assn. Ltd., Bui. 15, 
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1955. RELATIONSHIP OF ANTS TO FLY CONTROL IN PUERTO RICO; JOUr EcOD. 

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1940. A SURVEY OF THE PINEAPPLE MEALYBUG IN PUERTO RICO AND PRELIMINARY 

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102 TECHNICAL BULLETIN 1326, U.S. DEPT. OF AV;, 
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1908. THE LIFE HISTOEY OF THE CARPENTER ANT. Biol. Bui. 14 : 177-, 

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1934. NOTES ON THE BEHAVIOR OF CERTAIN ANTS OF ST. LOUIS COUNTY, M 

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1945. NOTES ON THE BEHAVIOR OF CERTAIN ANTS. Bnt. NeWS 56 : 118-121. 

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1962. CHICKEN AND TURKEY TAPEWORMS. Ga. Agr. Expt. Sta. Unnumbered 

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1944. RESULTS OF THE ARCHBOLD EXPEDITIONS NO. 81, BEHAVIOR AND ECOLOGICAL 
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1958. THE BEHAVIOR AND BIOLOGY OF CERTAIN NEARCTIC ARMY ANTS, LAST PART 
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1948. CONTROL OF ANTS IN TUBF AND SOIL. Conn. Agr. Expt. Sta. Bnl. 515, 

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1920. HOUSE ANTS. 8. Dak. State Ent. [Brookings] Cir. 20, 9pp. 

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1954. CARPENTER ANTS AND THEIR CONTROL. N.Y. State Col. of Forestry, Syra- 
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1962. THE STUDY OF ANTS. Scientific Book Club Edition, p; 12. Spottis- 
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1942. RELATIONSHIP OF INSECTS TO THE SPREAD OF AZALEA FLOWER SPOT. U.S. 

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1915 THE PAVEMENT ANT AS A PEST OF COLDFRAME AND GREENHOUSE CROPS. 

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1924. AN ANNOTATED LIST OF THE ANTS OF MISSISSIPPI. Bnt. News 35 : 77-85, 
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1927. A CONTRIBUTION TO THE BIOLOGY AND DISTRIBUTION OF ONE OF THE 

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1928. THE BIOLOGY OF TAPINOMA SESSILE SAY, AN IMPORTANT HOUSE-INFESTING 

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1936b. DISTRIBUTION OF THE ARGENTINE ANT IN THE UNITED STATES AND SUG- 
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1936c. THE ANTS OF PUERTO RICO. Puerto Rico Univ. Jour. Agr. 20: 819-875, 
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1939. THE TEXAS LEAF-CUTTING ANT (ATTA TEXAN A BUCKLEY) AND ITS CONTROL 

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1942. THE LEGIONARY ANTS OF THE UNITED STATES BELONGING TO ECITON SUB- 
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1943 A GENERIC AND BUBGENERIC SYNOPSIS OF THE -MALE ANTS OF THE UNITED 

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1947. A GENERIC AND SUBGENEWC SYNOPSIS OF THE UNITED STATES ANTB, BASED 

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HOUSE-INFESTING ANTS OF THE EASTERN UNITED STATES 103 

1950. (ORDER HYMENOPTERA, FAMILY FOBMICIDAE.) In Pest Control TeCh- 

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1928. LASIUS INTERJECTUS MAYR (FORMICIDAE) , A HOUSEHOLD PEST IN KANSAS. 

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1934. A SUMMARY OF PUBLISHED INFORMATION ABOUT PHARAOH'8 ANT, WITH 

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1910. INSECTS INJURIOUS TO FORESTS AND FOREST PRODUCTS. DAMAGE TO CHEST- 
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1941. THE SMALL FIRE ANT WASMANNIA IN CITRUS GROVES A PRELIMINARY 

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1929. SOIL INSECTS ATTACKING SUGAR CANE IN CUBA. TrOp. Plant ReS. Found. 

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1953. THE BEHAVIOR OF ANTS. COLONY FOUNDATION IN PHARAOH'S ANT (MONO- 

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1942. FORMICIDAE OF GUAM. / Insects of Guam 1. Bernice P. Bishop Mus. 
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1934. DISTRIBUTION OF ANT SPECIES IN THE CHICAGO REGION WITH REFERENCE 
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1943. POPULATION STUDIES OF THE ANT, PRENOLEPIS IMPABIS SAY. Ecology 24 : 



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1946. DAILY FLUCTUATIONS IN ABOVE GEOUND ACTIVITY OF THREE SPECIES OF 

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1951. POPULATIONS AND HIBERNATING CONDITIONS OF THE ANT, APHAENOGASTEB 

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1957. POPULATIONS OF ANTS IN A MISSOURI WOODLAND. Insectes Sociaux 4: 
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1945. LITERATURE OF THE BLACK CARPENTER ANT, CAMPONOTUS HERCULEANUS 
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1941. NOTES ON THE BIOLOGY OF THE FIBE ANT, 8OLENOPSIS GEMINATA (F.) IN 
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1958. THE ECOLOGY OF THE ANTS OF THE WELAKA RESERVE, FLORIDA. PART 2. 

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1963. HIGH ALTITUDE ANTS OF THE SOUTHERN BLUE RIDGE. Amer. Midland 

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104 TECHNICAL BULLETIN 1326, U.S. DEPT. OF AGRICULTURE 
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1910; CONTRIBUTIONS TO A KNOWLEDGE OF THE COBN BOOT APHIS. U.S. Dept. 

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1937. CONTROL OF THE PAVEMENT ANT ATTACKING EGGPLANTS. Jour. ECOU. Ent. 

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1942. ON ANT NESTING HABITS IN NORTH DAKOTA IN 1941 COMPABED WITH 

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1940. A COLLECTION OF ANTS FBOM souTH-CENTBAL OHIO. Amer. Midland Nat. 

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1944. THE ANTS OF NOBTH DAKOTA. N. Dak. Hist. Quart. 11 : 231-271. 
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1900. THE FEMALE OF ECITON 8UMICHBA8TI NOBTON, WITH SOME NOTES ON THE 

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19058. THE ANTS OF THE BAHAMAS, WITH A LIST OF THE KNOWN WEST INDIAN 

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1905b. AN ANNOTATED LIST OF THE ANTS OF NEW JERSEY. Amer. MUS. Nat. Hist. 

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1906a. THE ANTS OF THE GBAND CANYON. Amer. Mus. Nat. Hist. Bul. 22: 
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1906b. THE HABITS OF THE TENT-BUILDING ANT (OREMATOGASTEB LINEOLATA 

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1910a. THE NOBTH AMERICAN ANTS OF THE GENUS CAMPONOTUS MAYS. N. Y. 

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1910C. THE NOBTH AMEBICAN FORMS OF LASIUS UMBBATUS NYLANDEB. Psyche 

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1914. ANTS AND BEES AS CABBIEBS OF PATHOGENIC MICBO-OBGANISMS. Amer. 

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1916. FOBMICOIDEA. In Guide to the Insects of Connecticut. Part III, The 
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1922. (VII KEYS TO THE GENEBA AND SUBGENEBA OF ANTS.) In AntS Of the 

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1924. FOBMICIDAE OF THE HARBISON WILLIAMS GALAPAGOS EXPEDITION. ZOO- 

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1926. ANTS. THEIR STBUCTUBE, DEVELOPMENT AND BEHAVIOR. 2d edition. 

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1927. THE OCCUBRENCE OF THE PAVEMENT ANT (TETRAMORIUM CAESPITUM L.) 

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HOUSE-INFESTING ANTS OF THE EASTERN UNITED STATES 105 

1930. THE ANT PBENOLEPIS iMPABis SAY. Ent. Soc. Amer. Ann. 33: 1-26, 
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1932. A LIST OF THE ANTS OF FLORIDA WITH DESCRIPTIONS OF NEW FORMS. N. Y. 

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1903. DIMORPHIC QUEENS IN AN AMERICAN ANT (LASIUS LATIPES WALSH) . Blol. 

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1955. A MONOGRAPHIC REVISION OP THE ANT GENUS LASIUS. Harvard Univ., 

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1948. INSECTS OF PUEETO Bico. FOBMiciDAE (ANTS). Puerto Rico Univ. Jour. 

Agr.32: 810-839, figs. 
WROUGHTON, R. C. 

1892a. OUE ANTS. PAET i. Bombay Nat. Hist. Soc. Jour. 7 : 13-60, flgs. 
1892b. OUE ANTS. PARTH. Ibid. 7 : 175-203. 

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